BDMO 2020 regional questions for junior & secondary

1. 231 āϕ⧇ \[ \frac{1}{3} \] āĻĻāĻŋāϝāĻŧ⧇ āĻ­āĻžāĻ— āĻ•āϰ⧇ āĻĒā§āϰāĻžāĻĒā§āϤ āϏāĻ‚āĻ–ā§āϝāĻžāϕ⧇ āφāĻŦāĻžāϰ 3 āĻĻāĻŋāϝāĻŧ⧇ āϗ⧁āĻŖ āĻ•āϰāϞ⧇ āĻ•āϤ āĻĒāĻžāĻ“āϝāĻŧāĻž āϝāĻžāĻŦ⧇?

What will you get when 231 is divided by \[ \frac{1}{3} \] and the resultant again multiplied by 3?

2. S = 2020 + 2019 + 2018 + 2017 + ……… + 2 – 1āĨ¤ S āϕ⧇ 5 āĻĻā§āĻŦāĻžāϰāĻž āĻ­āĻžāĻ— āĻ•āϰāϞ⧇ āĻ­āĻžāĻ—āĻļ⧇āώ āĻ•āϤ āĻšāĻŦ⧇?

S=2020-2019+2018-2017+…………………+2-1 . What is the remainder when S is divided by 5?

3. 2310 āĻāϰ āϏāĻžāĻĨ⧇ 5 āϝ⧋āĻ— āĻ•āϰ⧇ āĻĒā§āϰāĻžāĻĒā§āϤ āϝ⧋āĻ—āĻĢāϞāϕ⧇ \[\frac{1}{5} \] āĻĻāĻŋāϝāĻŧ⧇ āĻ­āĻžāĻ— āĻ•āϰ⧇ āĻĒā§āϰāĻžāĻĒā§āϤ āϏāĻ‚āĻ–ā§āϝāĻžāϕ⧇ āφāĻŦāĻžāϰ 5 āĻĻāĻŋāϝāĻŧ⧇ āϗ⧁āĻŖ āĻ•āϰāϞ⧇ āĻ•āϤ āĻĒāĻžāĻ“āϝāĻŧāĻž āϝāĻžāĻŦ⧇?

Add 5 to 2310. Divide the result by 1/5 and then multiply by 5. Now, what is your final result

4. āĻāĻ•āϟāĻŋ āϏāĻŋāύ⧇āĻŽāĻž āĻšāϞ⧇ āĻĒā§āϰāĻĨāĻŽ āϏāĻžāϰāĻŋāϤ⧇ 11 āϟāĻŋ āφāϏāύ āφāϛ⧇āĨ¤ āĻĒāĻ°ā§āϝāĻžāϝāĻŧāĻ•ā§āϰāĻŽā§‡ āĻĒā§āϰāϤāĻŋāϟāĻŋ āϏāĻžāϰāĻŋāϤ⧇ āϤāĻžāϰ āϏāĻžāĻŽāύ⧇āϰ āϏāĻžāϰāĻŋāϰ āĻšā§‡āϝāĻŧ⧇ āĻāĻ•āϟāĻŋ āφāϏāύ āĻŦ⧇āĻļāĻŋ āφāϛ⧇āĨ¤ āϝāĻĻāĻŋ āĻŽā§‹āϟ āϏāĻžāϰāĻŋ āϏāĻ‚āĻ–ā§āϝāĻž 30 āϟāĻŋ āĻšāϝāĻŧ āϤāĻžāĻšāϞ⧇ āϏāĻŋāύ⧇āĻŽāĻž āĻšāϞ⧇ āĻŽā§‹āϟ āĻ•āϤāϟāĻŋ āφāϏāύ āφāϛ⧇?

The first row of a movie theater has 11 seats. Each successive row has one more seat than the previous row. What is the number of seats in the theater if there are 30 rows?

5. 2020 āĻāϰ āĻšā§‡āϝāĻŧ⧇ āϛ⧋āϟ āĻ•āϤāϗ⧁āϞ⧋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āϰāϝāĻŧ⧇āϛ⧇ āϝāĻžāĻĻ⧇āϰāϕ⧇ āϤāĻŋāύāϟāĻŋ āĻ•ā§āϰāĻŽāĻŋāĻ• āϧāύāĻžāĻ¤ā§āĻŽāĻ• āϏāĻ‚āĻ–ā§āϝāĻžāϰ āϝ⧋āĻ—āĻĢāϞ āĻšāĻŋāϏ⧇āĻŦ⧇ āϞ⧇āĻ–āĻž āϝāĻžāϝāĻŧ āύāĻž?

Find the number of positive numbers less than 2020, which can not be written as the sum of three consecutive positive numbers.

6. āϰ⧁āĻŦāĻžāĻŦ āĻāĻ•āϟāĻŋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻž āϚāĻŋāĻ¨ā§āϤāĻž āĻ•āϰāϞ⧋ āϝāĻž āĻ•āĻŋāύāĻž āĻāĻ•āϟāĻŋ āϘāύ āϏāĻ‚āĻ–ā§āϝāĻžāĨ¤ āϤāĻžāĻšāύāĻŋāĻ• āφāϰāĻ“ āĻāĻ•āϟāĻŋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻž āϚāĻŋāĻ¨ā§āϤāĻž āĻ•āϰāϞ⧋ āϝāĻž āĻ•āĻŋāύāĻž āĻŦāĻ°ā§āĻ—āϏāĻ‚āĻ–ā§āϝāĻžāĨ¤ āϤāĻžāĻĻ⧇āϰ āĻĻ⧁āχāϜāύ⧇āϰ āϏāĻ‚āĻ–ā§āϝāĻžāϰ āϝ⧋āĻ—āĻĢāϞ ā§Ēā§Ļ āĻšāϞ⧇ āϏāĻ‚āĻ–ā§āϝāĻžāĻĻ⧁āϟāĻŋāϰ āϗ⧁āĻŖāĻĢāϞ āĻ•āϤ?

Rubab thinks of a positive number that is a perfect cube, and Thanic thinks of a number that is a perfect square. If the sum of their numbers is 80, what is the product of their numbers?

7. āϤ⧋āĻŽāĻžāϰ āĻĻāĻļāϟāĻŋ āĻĒā§‹āρāĻļāĻž āĻ•āĻŦ⧁āϤāϰ āĻ›āĻŋāϞāĨ¤ āϤ⧁āĻŽāĻŋ āϤ⧋āĻŽāĻžāϰ āĻ•āϝāĻŧ⧇āĻ•āϜāύ āĻŦāĻ¨ā§āϧ⧁āϕ⧇ āϏ⧇āϗ⧁āϞ⧋ āĻ­āĻžāĻ— āĻ•āϰ⧇ āĻĻāĻŋāϤ⧇ āϚāĻžāĻ“āĨ¤ āĻĒā§āϰāĻĨāĻŽ āĻŦāĻ¨ā§āϧ⧁ āĻ›āϝāĻŧāĻŽāĻžāϏ⧇ āĻ•āϝāĻŧ⧇āĻ•āϟāĻŋ āĻ•āĻŦ⧁āϤāϰ āύāĻŋāϞāĨ¤ āĻāϰāĻĒāϰ āϝāϤāϗ⧁āϞ⧋ āĻ•āĻŦ⧁āϤāϰ āĻŦāĻžāϕ⧀ āφāϛ⧇, āϏ⧇āϗ⧁āϞ⧋ āĻŦāĻžāϕ⧀ āĻŦāĻ¨ā§āϧ⧁āĻĻ⧇āϰ āĻĒā§āϰāĻ¤ā§āϝ⧇āĻ•āϕ⧇ 3 āϟāĻŋ āĻ•āϰ⧇ āĻĻāĻŋāϞ 5 āϟāĻŋ āĻ…āĻŦāĻļāĻŋāĻˇā§āϟ āĻĨāĻžāϕ⧇ āĻāĻŦāĻ‚ 5 āϟāĻŋ āĻ•āϰ⧇ āĻĻāĻŋāϞ⧇āĻ“ 1 āϟāĻŋ āĻ…āĻŦāĻļāĻŋāĻˇā§āϟ āĻĨāĻžāϕ⧇āĨ¤ āĻĒā§āϰāĻĨāĻŽ āĻŦāĻ¨ā§āϧ⧁ āĻ•āϤāϟāĻŋ āĻ•āĻŦ⧁āϤāϰ āύāĻŋāϝāĻŧ⧇āĻ›āĻŋāϞ?

You have ten pigeons. You want to give these pigeons away to some of your friends. The first friend picks a number of pigeons of her choice for herself. After that you give away the remaining pigeons to the rest of your friends. If you give each of them 3 pigeons, 5 are left and if you give each of them 5 pigeons, 3 are left. How many pigeons did your first friend choose for herself?

8. āϝāĻĻāĻŋ \[ -8 \leq x \leq 2 \] āĻāĻŦāĻ‚ \[-4 \leq y \leq 10 \] āĻšāϝāĻŧ, āϤāĻžāĻšāϞ⧇ xy āĻāϰ āϏāĻ°ā§āĻŦā§‹āĻšā§āϚ āĻāĻŦāĻ‚ āϏāĻ°ā§āĻŦāύāĻŋāĻŽā§āύ āĻŽāĻžāύ⧇āϰ āĻŦāĻŋāϝāĻŧā§‹āĻ—āĻĢāϞ⧇āϰ āĻĒāϰāĻŋāĻŽāĻžāĻŖ āĻ•āϤ?

If -8≤x≤2 and -4≤y≤10, find the absolute difference of maximum and minimum value of xy.

9. āĻāĻ•āϟāĻž āĻā§āĻĄāĻŧāĻŋāϤ⧇ 100 āĻāϰ āĻšā§‡āϝāĻŧ⧇ āĻ•āĻŽ āϏāĻ‚āĻ–ā§āϝāĻ• āφāĻĒ⧇āϞ āφāϛ⧇āĨ¤ āφāĻĒ⧇āϞāϗ⧁āϞ⧋ 2, 3, 5 āϜāύ⧇āϰ āĻŽāĻ§ā§āϝ⧇ āύāĻŋāσāĻļ⧇āώ⧇ āĻ­āĻžāĻ— āĻ•āϰ⧇ āĻĻ⧇āϝāĻŧāĻž āϗ⧇āϞ⧇āĻ“ 4 āϜāύ⧇āϰ āĻŽāĻ§ā§āϝ⧇ āĻ­āĻžāĻ— āĻ•āϰ⧇ āĻĻ⧇āϝāĻŧāĻž āϝāĻžāϝāĻŧ āύāĻžāĨ¤ āϏāĻ°ā§āĻŦā§‹āĻšā§āϚ āĻ•āϤāϟāĻŋ āφāĻĒ⧇āϞ āĻĨāĻžāĻ•āĻž āϏāĻŽā§āĻ­āĻŦ āĻā§āĻĄāĻŧāĻŋāϤ⧇?

There are less than 100 apples in a basket. It is possible to divide the apples equally among 2, 3, and 5 children but not among 4 children. How many apples can there be in the basket at most?

10. āĻĒāĻžāρāϚāϟāĻŋ āϏāĻ‚āĻ–ā§āϝāĻžāϰ āĻ—āĻĄāĻŧ 7āĨ¤ āĻāĻĻ⧇āϰ āĻŽāĻ§ā§āϝ⧇ āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāϟāĻŋāϕ⧇ 3 āĻĻāĻŋāϝāĻŧ⧇ āϗ⧁āĻŖ āĻ•āϰāĻž āĻšāϞ⧇ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋āϰ āĻ—āĻĄāĻŧ 11 āĻšāĻŦ⧇?

The average of five numbers is 7. If one of the numbers is multiplied by 3, the average of the numbers increases to 11. Which of the five numbers is multiplied by 3?

11. \[ 2^p + 5^p = N \] āϝāĻĻāĻŋ p āĻŦāĻŋāĻœā§‹āĻĄāĻŧ āĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āĻšāϝāĻŧ, āϤāĻŦ⧇ N āϕ⧇ 3 āĻĻā§āĻŦāĻžāϰāĻž āĻ­āĻžāĻ— āĻ•āϰāϞ⧇ āĻ­āĻžāĻ—āĻļ⧇āώ āĻ•āϤ āĻšāĻŦ⧇?[ \[ x^p\] āĻĻāĻŋāϝāĻŧ⧇ āĻŦā§‹āĻāĻžāϝāĻŧ x āϕ⧇ p āĻŦāĻžāϰ āϗ⧁āĻŖ āĻ•āϰ⧇ āϗ⧁āĻŖāĻĢāϞ]

\[ 2^p + 5^p = N \] , if p is an odd prime number, what will be the remainder when dividing N by 3? [\[ x^p \] is x multiplied p times]

12. P, Q āĻĻ⧁āχāϟāĻŋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁āϰ āĻĻā§‚āϰāĻ¤ā§āĻŦ 10, Q āĻāĻŦāĻ‚ R āĻāχ āĻĻ⧁āχāϟāĻŋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁āϰ āĻĻā§‚āϰāĻ¤ā§āĻŦ 4 āĻāĻŦāĻ‚ R, S āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āĻĻ⧁āχāϟāĻŋāϰ āĻĻā§‚āϰāĻ¤ā§āĻŦ 3āĨ¤ P āĻāĻŦāĻ‚ S āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āĻĻ⧁āχāϟāĻŋāϰ āĻĻā§‚āϰāĻ¤ā§āĻŦ⧇āϰ āĻ¨ā§āϝ⧂āύāϤāĻŽ āĻ•āϤ āĻšāĻŦ⧇?

Points P and Q are 10 units apart. Points Q and R are 4 units apart. Points R and S are 3 units apart. If P and S are as close as possible, find the distance between P and S.

13. āϝ⧇ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋ āĻļ⧁āϧ⧁āĻŽāĻžāĻ¤ā§āϰ 1, 4, 6 āĻĻā§āĻŦāĻžāϰāĻž āĻ—āĻ āĻŋāϤ āĻšāϝāĻŧ āϏ⧇āχ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋ āϤ⧂āĻ°ā§āĻ¯ā§āϝ⧇āϰ āĻĒāĻ›āĻ¨ā§āĻĻ⧇āϰ āϏāĻ‚āĻ–ā§āϝāĻžāĨ¤ āϝ⧇āĻŽāύ: 1, 14, 146āĨ¤ āϤ⧂āĻ°ā§āϝ āϤāĻžāϰ āĻĒāĻ›āĻ¨ā§āĻĻ⧇āϰ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋ āϛ⧋āϟ āĻĨ⧇āϕ⧇ āĻŦāĻĄāĻŧ āĻšāĻŋāϏ⧇āĻŦ⧇ āϏāĻžāϜāĻŋāϝāĻŧ⧇ āĻĒā§āϰāĻĨāĻŽ 120 āϟāĻŋ āϏāĻ‚āĻ–ā§āϝāĻž āϝ⧋āĻ— āĻ•āϰāϞ⧋āĨ¤ āϝ⧋āĻ—āĻĢāϞāϕ⧇ 3 āĻĻāĻŋāϝāĻŧ⧇ āĻ­āĻžāĻ— āĻ•āϰāϞ⧇ āĻ­āĻžāĻ—āĻļ⧇āώ āĻ•āϤ āĻĨāĻžāĻ•āĻŦ⧇?

The positive integers that contain only 1,4,6 are Turzo’s favourite numbers. For example: 1, 14, 146. Turzo sorts his favourite numbers in asscending order and then sums the first 120 numbers. What will be the remainder if he divides the sum by 3?

14. āĻāĻ•āϟāĻŋ āĻŦāĻžāĻ•ā§āϏ⧇ 7 āϟāĻŋ āύ⧀āϞ āĻŦāϞ, 9āϟāĻŋ āϞāĻžāϞ āĻŦāϞ āĻāĻŦāĻ‚ 10āϟāĻŋ āϏāĻžāĻĻāĻž āĻŦāϞ āϰāϝāĻŧ⧇āϛ⧇āĨ¤ āĻĻ⧈āĻŦāϚ⧟āύ⧇ āĻŦāĻžāĻ•ā§āϰ āĻĨ⧇āϕ⧇ āĻāĻ•āϟāĻŋ āĻāĻ•āϟāĻŋ āĻ•āϰ⧇ āĻŦāϞ āωāĻ¤ā§āϤ⧋āϞāύ āĻ•āϰāĻž āĻšāϞ⧇āĻž āϝāϤāĻ•ā§āώāĻŖ āύāĻž āĻāĻ•āχ āϰāϙ⧇āϰ āϚāĻžāϰāϟāĻŋ āĻŦāϞ āĻ…āĻĨāĻŦāĻž āĻ¨ā§āϝ⧂āύāϤāĻŽ āĻĒā§āϰāĻ¤ā§āϝ⧇āĻ• āϰāϙ⧇āϰ āĻĻ⧁āχāϟāĻŋ āĻŦāϞ āωāĻ¤ā§āϤ⧋āϞāύ āĻ•āϰāĻž āĻšāϝāĻŧāĨ¤ āĻāĻ­āĻžāĻŦ⧇ āϏāĻ°ā§āĻŦā§‹āĻšā§āϚ āĻ•āϤāϟāĻŋ āĻŦāϞ āωāĻ¤ā§āϤ⧋āϞāύ āĻ•āϰāĻž āϝāĻžāĻŦ⧇?

A jar contains 7 blue balls, 9 red balls and 10 white balls. Balls are drawn at random one by one from the jar until either four balls of the same colour or at least two of each colour have been drawn. What is the largest number of balls that one may have to draw?

15. āĻāĻ•āϟāĻŋ āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻž, n āĻāϰ āϜāĻ¨ā§āϝ 5n+16 āĻāĻŦāĻ‚ 8n+29 āĻāϰ 1 āĻ…āĻĒ⧇āĻ•ā§āώāĻž āĻŦāĻĄāĻŧ āĻāĻ•āϟāĻŋ āϏāĻžāϧāĻžāϰāĻŖ āĻ‰ā§ŽāĻĒāĻžāĻĻāĻ• āϰāϝāĻŧ⧇āϛ⧇āĨ¤ āϏāĻžāϧāĻžāϰāĻŖ āĻ‰ā§ŽāĻĒāĻžāĻĻāĻ• āĻāϰ āĻŽāĻžāύ āĻ•āϤ?

For a certain integer n, 5n+16 and 8n+29 have a common factor larger than 1 . Find the common factor.

16. āĻāĻ•āϟāĻŋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻžāϰ āϏāĻŽāĻžāĻ¨ā§āϤāϰ āϧāĻžāϰāĻžāϰ āĻĒā§āϰāĻĨāĻŽ āĻĒāĻĻ 20 āĻāĻŦāĻ‚ āĻļ⧇āώ āĻĒāĻĻ 4060āĨ¤ āĻāχ āϰāĻ•āĻŽ āĻ•āϤāϟāĻŋ āĻ­āĻŋāĻ¨ā§āύ āĻ­āĻŋāĻ¨ā§āύ āϏāĻŽāĻžāĻ¨ā§āϤāϰ āϧāĻžāϰāĻž āϏāĻŽā§āĻ­āĻŦ?

An arithmetic sequence of integers has 20 as the first term and 4060 as the last term. How many different sets of integers form such a sequence?

17. 4, 5, 6, 8, 14, 38, ………… āĻāχ āϧāĻžāϰāĻžāϰ āĻĒāϰāĻŦāĻ°ā§āϤ⧀ āĻĒāĻĻ āϕ⧀?

4,5,6,8,14,38,……. what is the next number of this sequence?

18. āĻĒāĻžāĻļ⧇āϰ āϚāĻŋāĻ¤ā§āϰ⧇ ABCD āĻāĻ•āϟāĻŋ āϏāĻžāĻŽāĻžāĻ¨ā§āϤāϰāĻŋāĻ•āĨ¤ AB = 6, AC = 7, DE = 2āĨ¤ CF = a/b āĻāĻŦāĻ‚ gcd(a, b) = 1 āĻšāϞ⧇, a+b = ?BDMO 2020 regional questions for junior & secondary

ABCD is a parallelogram. If AB = 6, AC=7, DE=2. CF = a/b and gcd(a,b)=1. then, a+b =?

19. āĻœā§āϝ⧋āϤāĻŋāϰ āĻ•āĻžāϛ⧇ āĻĒā§āϰāϝāĻŧā§‹āϜāύ⧀āϝāĻŧ āϏāĻ‚āĻ–ā§āϝāĻ• 2 āϟāĻžāĻ•āĻžāϰ āĻāĻŦāĻ‚ 5 āϟāĻžāĻ•āĻžāϰ āύ⧋āϟ āϰāϝāĻŧ⧇āϛ⧇āĨ¤ āĻœā§āϝ⧋āϤāĻŋ āĻāĻ•āϟāĻŋ āϏ⧁āĻĒāĻžāϰ āĻļāĻĒ⧇ āĻ—āĻŋāϝāĻŧ⧇ 2020 āϟāĻžāĻ•āĻžāϰ āĻāĻ• āĻœā§‹āĻĄāĻŧāĻž āϜ⧁āϤāĻž āĻ•āĻŋāύāϞ⧋āĨ¤ āϏ⧇ āĻ•āϤāĻ­āĻžāĻŦ⧇ āĻ“āχ āϜ⧁āϤāĻžāϰ āĻĻāĻžāĻŽ āĻĻāĻŋāϤ⧇ āĻĒāĻžāϰāĻŦ⧇?

Juty has required numbers of 2 taka and 5 taka notes. Juty bought a pair of shoes with 2020 taka with those notes from a supershop. In how many ways Juty can pay for the shoes with those notes?

20. \[ a \times a – b \times b = n \], āϝ⧇āĻ–āĻžāύ⧇ n āĻāĻ•āϟāĻŋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻž āϝāĻž 101 āĻāϰ āĻšā§‡āϝāĻŧ⧇ āϛ⧋āϟāĨ¤ n-āĻāϰ āĻ•āϤāϗ⧁āϞ⧋ āĻŽāĻžāύ⧇āϰ āϜāĻ¨ā§āϝ a, b-āĻāϰ āĻŽāĻžāύ āϕ⧇āĻžāύ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻž āĻšāĻŦ⧇ āύāĻž?

a × a – b × b = n, where n is a positive integer less than 101. For how many values of n, both a and b will not be positive integers?

21. ABCD āĻāĻ•āϟāĻŋ āφāϝāĻŧāϤāĻ•ā§āώ⧇āĻ¤ā§āϰ āϝ⧇āĻ–āĻžāύ⧇ AB = 8 āĻāĻŦāĻ‚ AD = 6āĨ¤ DC āωāĻĒāϰ E, F āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āĻāĻŽāύāĻ­āĻžāĻŦ⧇ āĻ…āĻŦāĻ¸ā§āĻĨāĻŋāϤ āϝ⧇āύ DE = 3 āĻāĻŦāĻ‚ CF = 2āĨ¤ AF āĻāĻŦāĻ‚ BE āĻĒāϰāĻ¸ā§āĻĒāϰ H āĻŦāĻŋāĻ¨ā§āĻĻ⧁āϤ⧇ āϛ⧇āĻĻ āĻ•āϰ⧇āĨ¤ ∆AHB āĻāϰ āĻ•ā§āώ⧇āĻ¤ā§āϰāĻĢāϞ = \[ \frac{x}{11} \], āϝ⧇āĻ–āĻžāύ⧇ x āĻāĻ•āϟāĻŋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻžāĨ¤ x āĻāϰ āĻŽāĻžāύ āĻ•āϤ?

ABCD is a rectangle where AB=8 and AD=6. Points E and F are on the line segment DC where DE=3 and CF=2. Lines AF and BE intersect at point H.The area of ΔAHB = x/11, where x is a positive integer. What is the value of x?

22. p = q + r – s, q = r + s – p, r = s + p – q ; āĻāĻŦāĻ‚ \[ pqrs \neq 0 \] āĻšāϞ⧇ \[ \frac{p}{r} + \frac{q}{s} + \frac{r}{p} + \frac{s}{q} \] āĻāϰ āĻŽāĻžāύ āĻ•āϤ āĻšāĻŦ⧇?

p=q+r-s;q=r+s-p;r=s+p-q; And pqrs≠0 then what is the value of \[ \frac{p}{r} + \frac{q}{s} + \frac{r}{p} + \frac{s}{q} \]?

23. āϝāĻĻāĻŋ \[ x + \frac{1}{x} = 2\], āϤāĻžāĻšāϞ⧇ \[ x^{2020} + \frac{1}{x^{2019}} (x^{2019} + \frac{1}{x^{2020}}) \] āĻāϰ āĻŽāĻžāύ āĻ•āϤ āĻšāĻŦ⧇?

If \[ x + \frac{1}{x} = 2\], then what is the value of \[ x^{2020} + \frac{1}{x^{2019}} (x^{2019} + \frac{1}{x^{2020}}) \]?

24. āĻāĻ•āϟāĻŋ āĻ›āϝāĻŧ āĻĒ⧃āĻˇā§āĻ āĻŦāĻŋāĻļāĻŋāĻˇā§āϟ āĻ›āĻ•ā§āĻ•āĻžāϝāĻŧ 1 āĻĨ⧇āϕ⧇ 6 āĻāχ āĻ›āϝāĻŧāϟāĻŋ āϏāĻ‚āĻ–ā§āϝāĻž āĻāĻŽāύāĻ­āĻžāĻŦ⧇ āϞ⧇āĻ–āĻž āφāϛ⧇ āϝ⧇āύ āϝ⧇ āϕ⧋āύ āĻāĻ•āϟāĻŋ āĻĒ⧃āĻˇā§āĻ  āĻāĻŦāĻ‚ āϤāĻžāϰ āĻ…āĻĒāϰ āĻĒ⧃āĻˇā§āϠ⧇āϰ āϏāĻ‚āĻ–ā§āϝāĻžāϰ āϝ⧋āĻ—āĻĢāϞ 7 āĻšāϝāĻŧāĨ¤ āĻĒāĻžāĻļ⧇āϰ āϚāĻŋāĻ¤ā§āϰ⧇ āĻĻ⧁āϟāĻŋ āĻāĻ•āχ āϰāĻ•āĻŽ āĻ›āĻ•ā§āĻ•āĻž āĻĒāĻžāĻļāĻžāĻĒāĻžāĻļāĻŋ āϰāϝāĻŧ⧇āϛ⧇āĨ¤ āϝ⧇ āĻĻ⧁āϟāĻŋ āĻĒ⧃āĻˇā§āĻ  āĻāϕ⧇ āĻ…āĻĒāϰ⧇āϰ āϏāĻžāĻĨ⧇ āĻ¸ā§āĻĒāĻ°ā§āĻļ⧇ āϰāϝāĻŧ⧇āϛ⧇ āϤāĻžāĻĻ⧇āϰ āϝ⧋āĻ—āĻĢāϞ āĻ•āϤ?%Focuse keyword%

In a standard six-sided die, numbers from 1 to 6 are placed in such order, that sum of any side and its opposite side is 7. Two identical standard six-sided dice are placed side by side as shown. What is the sum of the numbers of dots on the two faces that touch each other?

 

Secondary level

1. 2020 āĻāϰ āĻ•āϤāϗ⧁āϞ⧋ āĻœā§‹āĻĄāĻŧ āĻ‰ā§ŽāĻĒāĻžāĻĻāĻ• āφāϛ⧇?

How many even divisors does 2020 have?

2. āĻāĻ•āϟāĻŋ āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āϤāĻŋāύ āĻŦāĻžāĻšā§āϰ āĻĻ⧈āĻ°ā§āĻ˜ā§āϝ āϝāĻĨāĻžāĻ•ā§āϰāĻŽā§‡ 4, 6 āĻāĻŦāĻ‚ 9āĨ¤ āĻ…āĻĒāϰ āĻāĻ•āϟāĻŋ āϏāĻĻ⧃āĻļ āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āĻāĻ• āĻŦāĻžāĻšā§āϰ āĻĻ⧈āĻ°ā§āĻ˜ā§āϝ 36āĨ¤ āĻĻā§āĻŦāĻŋāϤ⧀āϝāĻŧ āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āϏāĻ°ā§āĻŦā§‹āĻšā§āϚ āĻĒāϰāĻŋāϏ⧀āĻŽāĻž āĻ•āϤ āĻšāϤ⧇ āĻĒāĻžāϰ⧇?

The side lengths of a triangle are 4, 6 and 9. One of the side lengths of a triangle similar to the first triangle is 36. What is the maximum possible perimeter of the second triangle?

3. āĻ•āϤāϗ⧁āϞ⧋ āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻž p āĻāϰ āϜāĻ¨ā§āϝ p × p + 2 × p – 19 āĻāχ āϰāĻžāĻļāĻŋāϟāĻŋāϰ āĻāĻ•āϟāĻŋ āĻ‹āύāĻžāĻ¤ā§āĻŽāĻ• āĻŽāĻžāύ āφāϏāĻŦ⧇?

For how many integer values of p does the expression p × p + 2 × p – 19 have a negative value‘?

4. āĻāĻ•āϟāĻŋ āϏāĻŽāϕ⧋āĻŖā§€ āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āϤāĻŋāύ āĻŦāĻžāĻšā§āϰ āĻĻ⧈āĻ°ā§āĻ˜ā§āϝ āϝāĻĨāĻžāĻ•ā§āϰāĻŽā§‡ x – 7, x, āĻāĻŦāĻ‚ x + 2 āĻšāϞ⧇ āĻ¤ā§āϰāĻŋāϭ⧁āϜāϟāĻŋāϰ āĻĒāϰāĻŋāϏ⧀āĻŽāĻž āĻ•āϤ āĻšāĻŦ⧇?

The lengths of the sides of a right triangle are x-7, x, x+2. Find the numeric value of the perimeter of the triangle.

5. āĻ•āϤāϗ⧁āϞ⧋ 3 āĻ…āĻ™ā§āĻ• āĻŦāĻŋāĻļāĻŋāĻˇā§āϟ āϏāĻ‚āĻ–ā§āϝāĻž āĻĒāĻžāĻ“āϝāĻŧāĻž āϝāĻžāĻŦ⧇ āϝ⧇āĻ–āĻžāύ⧇ āĻ…āĻ™ā§āĻ• āϤāĻŋāύāϟāĻŋ āĻāĻ•āϟāĻŋ āϧāύāĻžāĻ¤ā§āĻŽāĻ• āϏāĻŽāĻžāĻ¨ā§āϤāϰ āĻ…āύ⧁āĻ•ā§āϰāĻŽ āĻŽā§‡āύ⧇ āϚāϞ⧇?

How many 3 digits number are there such that their digits are in arithmatic progression with positive difference?

6. n āĻāĻ•āϟāĻŋ āĻĒāĻžāρāϚ āĻ…āĻ™ā§āĻ• āĻŦāĻŋāĻļāĻŋāĻˇā§āϟ āĻĒā§āϝāĻžāϞāĻŋāύāĻĄā§āϰ⧋āĻŽāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āĻāĻŦāĻ‚ 7n āĻāĻ•āϟāĻŋ āĻ›āϝāĻŧ āĻ…āĻ™ā§āĻ•āĻŦāĻŋāĻļāĻŋāĻˇā§āϟ āĻĒā§āϝāĻžāϞāĻŋāύāĻĄā§āϰ⧋āĻŽāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āĻšāϞ⧇ n āĻāϰ āϏāĻ°ā§āĻŦā§‹āĻšā§āϚ āĻŽāĻžāύ āĻ•āϤ?

What is the greatest 5-digit palindrome n such that 7n is a 6-digit palindrome?

7. āĻāĻ•āϟāĻŋ āϏāĻŽāĻŦāĻžāĻšā§ āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āĻĒā§āϰāĻ¤ā§āϝ⧇āĻ• āĻŦāĻžāĻšā§āϕ⧇ āĻāĻŽāύ āĻ­āĻžāĻŦ⧇ āĻĻ⧁āχ āĻ­āĻžāϗ⧇ āĻ­āĻžāĻ— āĻ•āϰāĻž āĻšāϝāĻŧ⧇āϛ⧇ āϝ⧇āύ āĻ…āĻ‚āĻļ āĻĻ⧁āϟāĻŋāϰ āĻŽāĻ§ā§āϝ⧇ āĻ…āύ⧁āĻĒāĻžāϤ 4:1 āĻšāϝāĻŧāĨ¤ āĻŦāĻŋāĻ­āĻ•ā§āϤāĻ•āĻžāϰ⧀ āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āϤāĻŋāύāϟāĻŋ āĻĻāĻŋāϝāĻŧ⧇ āĻāĻ•āϟāĻŋ āϏāĻŽāĻŦāĻžāĻšā§ āĻ¤ā§āϰāĻŋāϭ⧁āϜ āĻ—āĻ āĻŋāϤ āĻšāϝāĻŧāĨ¤ āϝāĻĻāĻŋ āϛ⧋āϟ āĻ¤ā§āϰāĻŋāϭ⧁āϜ āĻāĻŦāĻ‚ āĻŦāĻžāĻšāĻŋāϰ⧇āϰ āĻŦāĻĄāĻŧ āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āĻ•ā§āώ⧇āĻ¤ā§āϰāĻĢāϞ⧇āϰ āĻ…āύ⧁āĻĒāĻžāϤ a/b āĻšāϝāĻŧ, āϝ⧇āĻ–āĻžāύ⧇ a, b āĻĒāϰāĻ¸ā§āĻĒāϰ āϏāĻšāĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž, āϤāĻžāĻšāϞ⧇ a+b āĻāϰ āĻŽāĻžāύ āĻ•āϤ?%Focuse keyword%

The sides of an equilateral triangle are divided into pieces that are in the ratio of 4:1 in such a way that the dividing points also form an equilateral triangle (see figure). Ratio of the area of the smaller equilateral triangle to the area of the larger equilateral triangle is equalt to a/b where a and b are coprime then find a+b

8. ABC āĻāĻ•āϟāĻŋ āϏāĻŽāϕ⧋āĻŖā§€ āĻ¤ā§āϰāĻŋāϭ⧁āϜ āϝ⧇āĻ–āĻžāύ⧇ AC=6 āĻāĻŦāĻ‚ CB=4āĨ¤ āĻāĻ•āϟāĻŋ āĻ…āĻ°ā§āϧāĻŦ⧃āĻ¤ā§āϤ āĻ…āĻ™ā§āĻ•āύ āĻ•āϰāĻž āĻšāϞ⧋ āϝāĻžāϰ āϕ⧇āĻ¨ā§āĻĻā§āϰ āĻ…āϤāĻŋāϭ⧁āĻœā§‡āϰ āĻ“āĻĒāϰ āĻ…āĻŦāĻ¸ā§āĻĨāĻŋāϤ āĻāĻŦāĻ‚ āĻ…āĻ°ā§āϧāĻŦ⧃āĻ¤ā§āϤāĻŋ āĻ…āĻĒāϰ āĻĻ⧁āχ āĻŦāĻžāĻšā§āϕ⧇ āĻ¸ā§āĻĒāĻ°ā§āĻļ āĻ•āϰ⧇āĨ¤ āϝāĻĻāĻŋ āĻ…āĻ°ā§āϧāĻŦ⧃āĻ¤ā§āϤāϟāĻŋ āĻŦā§āϝāĻžāϏāĻžāĻ°ā§āϧ a/b āĻšāϝāĻŧ āϝ⧇āĻ–āĻžāύ⧇ a, b āĻĒāϰāĻ¸ā§āĻĒāϰ āϏāĻšāĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž, āϤāĻžāĻšāϞ⧇ a+b āĻāϰ āĻŽāĻžāύ āĻ•āϤ?%Focuse keyword%

In a right angle triangle ABC , AC=6 and CB=4, we construct a halfcircle with center on the hypotenuse and being tangent to the rectangular sides. If the radius of the semi circle is a/b where a,b are co-prime ,determine a+b.

9. ABC āĻāĻ•āϟāĻŋ āϏāĻŽāϕ⧋āĻŖā§€ āĻ¤ā§āϰāĻŋāϭ⧁āϜ āϝāĻžāϰ AB=30 āĻāĻŦāĻ‚ BC=40āĨ¤ A āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āĻĨ⧇āϕ⧇ āĻŽāĻ§ā§āϝāĻŽāĻž AD āĻāĻŦāĻ‚ āϕ⧋āϪ⧇āϰ āϏāĻŽāĻĻā§āĻŦāĻŋāĻ–āĻ¨ā§āĻĄāĻ• AE āĻ…āĻ™ā§āĻ•āύ āĻ•āϰāĻž āĻšāϞ⧋āĨ¤ AED āĻ¤ā§āϰāĻŋāϭ⧁āĻœā§‡āϰ āĻ•ā§āώ⧇āĻ¤ā§āϰāĻĢāϞ āĻ•āϤ?%Focuse keyword%

ABC is a right angle triangle where AB=30 and BC=40. If we draw the median AD and the bisector AE from point A, we obtain a new triangle AED. Determine the area of that triangle.

10. 2, 3, …, 100 āĻāĻ­āĻžāĻŦ⧇ 99āϟāĻŋ āϏāĻ‚āĻ–ā§āϝāĻž āĻĻ⧇āĻ“āϝāĻŧāĻž āφāϛ⧇āĨ¤ 5āϜāύ āĻŦāĻ¨ā§āϧ⧁ āĻŽāĻŋāϞ⧇ āϤ⧁āĻŽāĻŋ āĻāχ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋ āύāĻŋāϝāĻŧ⧇ āϖ⧇āϞāϛ⧋āĨ¤ āĻĒā§āϰāĻĨāĻŽā§‡ āϤ⧁āĻŽāĻŋ 2āĻāϰ āϏāĻŦ āϗ⧁āĻŖāĻŋāϤāĻ• āĻŦāĻžāĻĻ āĻĻāĻŋāϝāĻŧ⧇ āĻĻāĻžāĻ“, āĻāϰāĻĒāϰ⧇āϰ āĻŦāĻ¨ā§āϧ⧁ āĻāϏ⧇ āĻ…āĻŦāĻļāĻŋāĻˇā§āϟ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋āϰ āĻŽāĻ§ā§āϝ⧇ āϏāĻŦāĻšā§‡āϝāĻŧ⧇ āϛ⧋āϟ āϏāĻ‚āĻ–ā§āϝāĻžāϟāĻŋāϰ āϏāĻ•āϞ āϗ⧁āĻŖāĻŋāϤāĻ• āĻŦāĻžāĻĻ āĻĻāĻŋāϝāĻŧ⧇ āĻĻ⧇āϝāĻŧ, āϤāĻžāϰāĻĒāϰ⧇āϰ āĻŦāĻ¨ā§āϧ⧁ āĻ…āĻŦāĻļāĻŋāĻˇā§āϟ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋āϰ āĻŽāĻžāĻā§‡ āĻ•ā§āώ⧁āĻĻā§āϰāϤāĻŽ āϏāĻ‚āĻ–ā§āϝāĻžāϟāĻŋāϰ āϏāĻ•āϞ āϗ⧁āĻŖāĻŋāϤāĻ• āĻŦāĻžāĻĻ āĻĻāĻŋāϤ⧇ āĻĨāĻžāϕ⧇ āĻāĻ­āĻžāĻŦ⧇ āϖ⧇āϞāĻžāϟāĻŋ āϚāϞāϤ⧇ āĻĨāĻžāϕ⧇āĨ¤ āϤ⧋āĻŽāĻžāĻĻ⧇āϰ āĻŽāĻ§ā§āϝ⧇ āϝāĻžāϰ āĻ•āĻžāϛ⧇ āφāϰ āĻŦāĻžāĻĻ āĻĻ⧇āĻ“āϝāĻŧāĻžāϰ āĻŽāϤ⧋ āϏāĻ‚āĻ–ā§āϝāĻž āĻĨāĻžāĻ•āĻŦ⧇ āύāĻž āϏ⧇ āϖ⧇āϞāĻžāϟāĻŋ āϜāĻŋāϤ⧇ āϝāĻžāϝāĻŧāĨ¤ āĻāχ āϖ⧇āϞāĻžāϟāĻŋāϤ⧇ āĻ•āϤāϤāĻŽ āĻŦā§āϝāĻ•ā§āϤāĻŋ āϜāĻŋāϤ⧇ āϝāĻžāϝāĻŧ?

99 numbers are given in the order: 2,3,â€Ļ,100. 5 friends including you are playing with these numbers. At first you remove all the multiples of 2. The next friend comes and removes the multiples of next remaining smallest number. And this goes in repeated process. The person who doesn’t have anything to remove wins the game. What will be the serial of the winner?

11. āĻĒāĻžāĻļ⧇āϰ āϚāĻŋāĻ¤ā§āϰāϟāĻŋāϤ⧇ P, AB āĻāϰ āωāĻĒāϰ āĻāĻŽāύ āĻāĻ•āϟāĻŋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āϝ⧇āύ AP:PB = 5:4āĨ¤ PQ āĻāĻŦāĻ‚ AC āĻĒāϰāĻ¸ā§āĻĒāϰ āϏāĻŽāĻžāĻ¨ā§āϤāϰāĻžāϞ āĻāĻŦāĻ‚ CP āĻāĻŦāĻ‚ QD āĻĒāϰāĻ¸ā§āĻĒāϰ āϏāĻŽāĻžāĻ¨ā§āϤāϰāĻžāϞāĨ¤ AR āĻāĻŦāĻ‚ QS, CP āĻāϰ āωāĻĒāϰ āϞāĻŽā§āĻŦ āĻāĻŦāĻ‚ QS = 6āĨ¤ āϤāĻžāĻšāϞ⧇ AP:PD = a/b āϝ⧇āĻ–āĻžāύ⧇ a, b āĻĒāϰāĻ¸ā§āĻĒāϰ āϏāĻšāĻŽā§ŒāϞāĻŋāĻ• āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž, āϤāĻžāĻšāϞ⧇ a+b = ?%Focuse keyword%

In the figure given below, P is a point on AB such that AP:PB=5:4 . PQ is parallel to AC and QD is parallel to CP. AR and QS are perpendicular to CP. Length of QS=6 then ratio of AP:PD=a/b where a,b are relatively coprime and positive number. Then a+b=?

12. ABC āĻāĻ•āϟāĻŋ āϏāĻŽāϕ⧋āĻŖā§€ āĻ¤ā§āϰāĻŋāϭ⧁āϜāĨ¤ āĻ¤ā§āϰāĻŋāϭ⧁āϜāϟāĻŋāϰ āĻĒāϰāĻŋāϕ⧇āĻ¨ā§āĻĻā§āϰ O, āϞāĻŽā§āĻŦāϕ⧇āĻ¨ā§āĻĻā§āϰ H, F, AB āϰ⧇āĻ–āĻžāĻ‚āĻļ⧇ āĻ…āĻŦāĻ¸ā§āĻĨāĻŋāϤ āĻāĻ•āϟāĻŋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁, AH āĻāϰ āĻŽāĻ§ā§āϝāĻŦāĻŋāĻ¨ā§āĻĻ⧁ M āĻāĻŦāĻ‚ OF || BCāĨ¤
āϕ⧋āĻŖ FMC āĻāϰ āĻŽāĻžāύ āĻĄāĻŋāĻ—ā§āϰāĻŋāϤ⧇ āĻ•āϤ?

Let ABC be an acute triangle.Let OF || BC where O is the circumcenter and F is between A and B.Let H be the orthocenter.Let M be the midpoint of AH. What is the value of angle FMC in degrees?

13. āĻāĻŦāĻžāϰ⧇āϰ IMO āϤ⧇ āϏāĻŋāĻĻā§āϧāĻžāĻ¨ā§āϤ āύ⧇āĻ“āϝāĻŧāĻž āĻšāϞ āĻĒā§āϰāϤāĻŋ āϟāĻŋāĻŽā§‡ 10 āϜāύ āĻ•āϰ⧇ āϏāĻĻāĻ¸ā§āϝ āĻĨāĻžāĻ•āĻŦ⧇āĨ¤ āϟāĻŋāĻŽā§‡āϰ āĻ…āĻ¨ā§āϤāϤ āĻĻ⧁āχāϜāύ⧇āϰ āĻāĻ•āχ āĻĻāĻŋāύ⧇ āϜāĻ¨ā§āĻŽāĻĻāĻŋāύ āĻšāĻŦāĻžāϰ āϏāĻŽā§āĻ­āĻžāĻŦāύāĻž āĻ•āϤ?

In this years IMO a deceision has been taken that each team will be consist of 10 members. What is the probability that at least two person will have birthday in same day of the week?

14. āĻāĻŽāύ āϏāĻ•āϞ (x, y, z); (x < y < z) āĻā§Ÿā§€āϰ āϏāĻŽāĻˇā§āϟāĻŋ āĻŦ⧇āϰ āĻ•āϰ āϝ⧇āĻ–āĻžāύ⧇ x, y, z, z-y, y-x, z-x āĻŽā§ŒāϞāĻŋāĻ• āĻšāϝāĻŧāĨ¤ (āϏāĻ•āϞ āĻā§Ÿā§€āϰ āϏāĻŽāĻˇā§āϟāĻŋ āĻŦ⧇āϰ āĻ•āϰ⧇ āϏ⧇āχ āϏāĻŽāĻˇā§āϟāĻŋāϗ⧁āϞ⧋āϰ āϏāĻŽāĻˇā§āϟāĻŋ āύāĻŋāĻ°ā§āĻŖāϝāĻŧ āĻ•āϰāϤ⧇ āĻšāĻŦ⧇āĨ¤)

Find the sum of all triples (x, y, z ; (x<y<z) ) such that x, y, z, z-y, y-x, z-x are all prime positive integers. (First sum all the triples individually, then summ all the sums.)

15. 1, 2, 3, 4, 5, 6 āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋āϕ⧇ āϞāĻžāϞ, āϏāĻŦ⧁āϜ āφāϰ āύ⧀āϞ āϰāĻ‚ āĻĻāĻŋāϝāĻŧ⧇ āĻ•āϤāĻ­āĻžāĻŦ⧇ āϰāĻ‚ āĻ•āϰāĻž āϝāĻžāϝāĻŧ āϝ⧇āύ āϕ⧋āύ⧋ āϏāĻ‚āĻ–ā§āϝāĻž āφāϰ āϤāĻžāϰ āϕ⧋āύ⧋ āĻĒā§āϰāĻ•ā§ƒāϤ āĻ‰ā§ŽāĻĒāĻžāĻĻāϕ⧇āϰ āϰāĻ‚ āĻāĻ•āχ āύāĻž āĻšāϝāĻŧ? (āϕ⧋āύ⧋ āϏāĻ‚āĻ–ā§āϝāĻžāϰ āĻĒā§āϰāĻ•ā§ƒāϤ āĻ‰ā§ŽāĻĒāĻžāĻĻāĻ•āϗ⧁āϞ⧋ āĻšāϞ⧋ āϏ⧇ āύāĻŋāĻœā§‡ āĻŦāĻžāĻĻ⧇ āĻŦāĻžāĻ•āĻŋ āĻ‰ā§ŽāĻĒāĻžāĻĻāĻ•āϗ⧁āϞ⧋)āĨ¤

How many ways are there to color the numbers 1, 2, 3, 4, 5, 6 with the colors red, green and blue such that no number is colored the same as one of its proper divisors? (The proper divisors of a number are the divisors that are not equal to the number itself)

16. a₁ + a₂ + a₃ + … āĻāĻ•āϟāĻž āĻ…āϏ⧀āĻŽ āϗ⧁āĻŖā§‹āĻ¤ā§āϤāϰ āϧāĻžāϰāĻž āϝāĻžāϰ āϏāĻŽāĻˇā§āϟāĻŋ 3āĨ¤ āϧāĻžāϰāĻžāϟāĻŋāϰ āĻĒā§āϰāϤāĻŋāϟāĻž āĻĒāĻĻāϕ⧇ āϤāĻžāϰ āĻŦāĻ°ā§āĻ— āĻĻāĻŋāϝāĻŧ⧇ āĻŦāĻĻāϞ⧇ āĻĻāĻŋāϞ⧇ āϤāĻžāϰ āϏāĻŽāĻˇā§āϟāĻŋ āĻ…āĻĒāϰāĻŋāĻŦāĻ°ā§āϤāĻŋāϤ āĻĨāĻžāϕ⧇āĨ¤ āϧāĻžāϰāĻžāϟāĻŋāϰ āĻĒā§āϰāϤāĻŋāϟāĻž āĻĒāĻĻāϕ⧇ āϤāĻžāϰ āϘāύ āĻĻāĻŋāϝāĻŧ⧇ āĻŦāĻĻāϞ⧇ āĻĻāĻŋāϞ⧇ āĻĒāϰāĻŋāĻŦāĻ°ā§āϤāĻŋāϤ āϧāĻžāϰāĻžāϟāĻŋāϰ āϏāĻŽāĻˇā§āϟāĻŋāϕ⧇ a/b āφāĻ•āĻžāϰ⧇ āĻĒā§āϰāĻ•āĻžāĻļ āĻ•āϰāĻž āϝāĻžāϝāĻŧ āϝ⧇āĻ–āĻžāύ⧇ a āĻāĻŦāĻ‚ b āĻĒāϰāĻ¸ā§āĻĒāϰ āϏāĻšāĻŽā§ŒāϞāĻŋāĻ• āϧāύāĻžāĻ¤ā§āĻŽāĻ• āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻžāĨ¤ āϤāĻžāĻšāϞ⧇ (a+b) āĻ•āϤ?

a₁ + a₂ + a₃ + …is an infinite geometric series whose sum is 3. Replacing each of the terms of the series by their squares results in a series whose sum is the same. Replacing each of the terms of the series by their cubes results in a series whose sum can be expressed by a/b where a and b are co-pime positive integers. What is a+b?

17. āĻ•āϤāϗ⧁āϞ⧋ āĻĒā§‚āĻ°ā§āĻŖāϏāĻ‚āĻ–ā§āϝāĻžāϰ āĻœā§‹āĻĄāĻŧāĻž (a, b) āφāϛ⧇ āϝ⧇āĻ–āĻžāύ⧇ 100 ≤ a, b ≤ 200 āĻāĻŦāĻ‚ a+b āĻāϰ āĻ•āϰāĻžāϰ āϏāĻŽāĻ°ā§āĻĨāύ āϏāĻŽā§āϝāĻ• āĻšāϤ⧇ āĻ•āĻŋāϛ⧁ āϰāĻžāϖ⧇ āϞāĻžāϗ⧇ āύāĻž?

How many ordered pairs of integers (a, b) are there such that 100 ≤ a, b ≤ 200 and no carrying is required when calculating a+b?

18. āĻļ⧁āϧ⧁ 1, 2, 3, āĻ…āĻ•ā§āώāϰāϗ⧁āϞ⧋ āĻŦā§āϝāĻŦāĻšāĻžāϰ āĻ•āϰ⧇ āĻ—āĻ āĻŋāϤ āϏāĻ‚āĻ–ā§āϝāĻžāϗ⧁āϞ⧋āϕ⧇ āωāĻĻā§āĻ­āĻžāĻŦāύ⧇āϰ āϞ⧇āĻ–āĻžāϰ āĻšāϞ⧋: 1, 2, 3, 11, 12, 13, …āĨ¤ 2020-āϤāĻŽ āϏāĻ‚āĻ–ā§āϝāĻžāϟāĻŋ āϕ⧀ āĻšāĻŦ⧇?

The numbers obtained by only using the digits 1, 2 and 3 are written in ascending order: 1, 2, 3, 11, 12, 13, … . What is the 2020-th number in this sequence?

 

BdMO-2020-All-Problem-Set

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