Jennifer buys a smartphone with a case for $200. The smartphone costs $180 more than the case. What is the cost of the case?

[A solution to this problem will appear along with next month’s problem.]


As shown, three 3-digit numbers have a 4-digit sum. Different letters represent different digits. What is the greatest prime factor of the sum, ACCA?

[ 37 ]


An inexpensive toy normally sells for 20 cents each. At a special reduced price, a store sold all of its toys, one at a time, for a total of $3.91. How many of these toys were sold if the reduced price is a whole number of cents?

[ 23 (at 17 cents each) ]



David removes 30% of the water in a jar. He then removes 40% of what remains in the jar. What percent of the original amount of water is now in the jar?

[ 42% ]


Visit our MOEMS Classic page Problem of the Month for detailed solutions

Copyright © 2017by Mathematical Olympiads for Elementary and Middle Schools, Inc. All rights reserved.


For many additional problems we highly recommend the following books:

Math Olympiad Contest Problems for Elementary and Middle Schools by Dr. G. Lenchner
Math Olympiad Contest Problems Volume 2 edited by Richard Kalman
MOEMS® Contest Problems Volume 3
edited by Richard Kalman & Nicholas J. Restivo.
are sources of many such problems.

Creative Problem Solving in School Mathematics 2nd Edition by Dr. George Lenchner
can help you to teach solving these types of problems