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 105 by the denominator 21:
105 (numerator) ÷ 21 (denominator) = 5
As a result, you get 5 as your answer when you convert 4 21/21 (or 105/21) to a decimal.