400
List all factors of 16:
List all factors of 24:
Find the Greatest Common Factor of 16 and 24
Why is this useful information? :-)
16: 1, 2, 4, 8, 16
24: 1, 2, 3, 4, 6, 8, 12, 24
GCF: 8
If I wanted to reduce 16/24, the shortest way would be to divide numerator and denominator by the GCF!