Charlotte Math Meetup


The Level E problems can be solved by elementary school math. They are designed from CMM Level E students, though students in Level M may find them interesting too. The answer to each problem should be a number. Please also report how many minutes it takes you to finish each problem. Do not rush. Do not use a calculator.

11th Assignment (Due: 8:00pm ET, June 2, 2020)

E1. What's the sum of digits of 999,999,999 × 666,666?

E2. What's the greatest common factor of 25200, 14850 and 8190?

E3. In the following expression, ONE + TWO + FOUR = SEVEN, different letters represent different nonnegative integers. What's the largest possible value for V?

E4. During the COVID-19 lock down, CMM was conducted online. Many students don't know each other before. After the lock down, Dr. Hong invites a few CMM students to his house for a party. To make sure that the students can have fun with each other, Dr. Hong invites as many students as he can under the condition that among each three students, there are two who know each other and two who don't know each other. How many students were invited by Dr. Hong?

M1. The sum of 3 different positive integers is 55. The sum of any two of them is a perfect square. What is the median of these three positive integers?

M2. A circle is inscribed in a right triangle of leg lengths 8 and 15. What's the area of this circle? (Let Pi = 3.14.)

M3. In the year-end ceremony, 12 top-performing CMM students form a line. Each of them holds a different number from 1 to 12. Dr. Hong calls their numbers one at a time to give them awards. At first, Dr. Hong tries to call the numbers so that no three of them form an arithmetic sequence. What's the maximum number of students Dr. Hong calls before he sees an arithmetic sequence of at least three numbers.

Previous Meetups

  Date  Assignment  Solution 
WK1  3/24; 3/26  A1   
WK2  3/31; 4/2  A2   
WK3(E)  4/7  A3E  A3E 
WK3(M)  4/9  A3M  A3M 
WK4(E)  4/14  A4E  A4E 
WK4(M)  4/16  A4M  A4M 
WK5(E)  4/21  A5E  A5E 
WK5(M)  4/23  A5M  A5M 
WK6(E)  4/28  A6E  A6E 
WK6(M)  4/30  A6M  A6M 
WK7(E)  5/5  A7E  A7E 
WK7(M)  5/7  A7M  A7M 
WK8  5/14  A8E; A8M  A8 
WK9  5/21  A9E; A9M  A9 
WK10 5/28 A10E; A10M A10 
WK11 6/4