Question

A dime is about 1 mm thick. how many dimes are in a stack 1 cm high

Answer 1

There are 10 mm in a cm.

If each dime is 1 mm then 10 dimes will be 1 cm high

1 dime / 1 mm = x dimes / 10 mm Cross multiply

1 dime * 10 mm = x * 1 mm

10 dimes = x The mm cancel out.