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 12748 by the denominator 343 (which you can enter in any calculator):
12748 (numerator) ÷ 343 (denominator) = 37.17
And finally, you get 37.17 as your answer when you convert 36 400/343 (or 12748/343) to a decimal.

