Can someone help me with my math homework?

Question

my teacher wrote on the board LCD the listed 1-20(problems) and then for each problem she put one number now i thought u need two number for lcd...but anyway she wrote it kinda like this

LCD

1)25

2)66

3)25

...

Answer 1

LCD is lowest common denominator, but you don't have any fractions to compare.

lowest common multiple would also require 2 numbers and so would highest common divisor.  Not sure what your teach is looking for.