What is 8.21 as a fraction

Realize than any number n that "isn't" a fraction is equal to n/1

In this case:

8.21/1 now we want the numerator to be a whole number so we can multiply both the numerator and denominator by the same amount with changing its value

(8.21) 100/100

821/100 now this is an improper fraction so we should change it to a mixed number ...

(800+21) / 100

8+21/100

8 21/100