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 643 by the denominator 10 (which you can enter in any calculator):
643 (numerator) ÷ 10 (denominator) = 64.3
And finally, you get 64.3 as your answer when you convert 64 3/10 (or 643/10) to a decimal.