Forgetful Fran

Help Fran remember how much money she loaned each friend.

Measuring Exact Amounts

Can you produce exactly 3 gallons of water? 

The Horse Problem

How much does a man make or lose in the horse-trading business?

Paying for Lunch

What happened to the other dollar?

Magic Circle

Make the sum of all rows equal the same number.

Magic Hexagon

Make the sum of each of the rows equal certain numbers.  In the hexagons below, place the numbers 1-19 so that rows, columns and diagonals all add up to 38. (Source: Eric W. Weisstein) Extension: Place the numbers 1-19 in the circles so the sum of each of the rows with three circles around the […]

Magic Square

Make the sum of the numbers in the rows, columns, and diagonals of a grid all equal the same integer. 

Calendar Math

Will the sum of four numbers always be the same?

Those Numbers Below

Consider the use of the word “below” for negative numbers.

Cryptorithms

Translate letters into numbers.