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 138 by the denominator 12:
138 (numerator) ÷ 12 (denominator) = 11.5
As a result, you get 11.5 as your answer when you convert 10 18/12 (or 138/12) to a decimal.