A fraction is written in terms of two parts: the number on top is called the numerator and the number on the bottom is called the denominator. We can use the division method to solve this question. To get a decimal, simply divide the numerator 21 by the denominator 4:
21 (numerator) ÷ 4 (denominator) = 5.25
As a result, you get 5.25 as your answer when you convert 5 1/4 (or 21/4) to a decimal.