A fraction is usually split into two parts: the first part is the number on top, called the numerator; and the second part is the number on the bottom, called the denominator. These are both separated by a line called the “divisor line”. We can use the division method help to solve this question: to get a decimal, simply divide the numerator 125 by the denominator 10 (which you can enter in any calculator):
125 (numerator) ÷ 10 (denominator) = 12.5
And finally, you get 12.5 as your answer when you convert 8 45/10 (or 125/10) to a decimal.