MaTh
posted by meepolo .
Michal has 42 identical cubical blocks, each one with an edge of 1 cm. From all of these blocks, he built a rectangular prism with a base perimeter equal to 18 cm. What is the height of the prism which he built?

the area of the base is a factor of 42
with a perimeter of 18, the possible block arrangements are __
8 X 1 __ area 8
7 X 2 __ area 14
6 X 3 __ area 18
5 X 4 __ area 20
14 is the only factor of 42, so the height must be 3