21/42 in simplest form

First, we need to find the greatest common factor of 21 and 42, which is 21.

Dividing both 21 and 42 by the greatest common factor, we get: 

(21:21) / (42:21)

= ½ 

Therefore, the simplest form of 21/42 is ½. 

21 42 in simplest form