c programming

Write a function for determining if an input argument, a, is divisible by 9. Hint: the modulo operator (%) gives the remainder of an integer division. For example, 21 % 9 = 3 (because the integer division has a remainder of 3: 21/9 = 2 R 3). The function should return 1 if the input argument is divisible by 9.

Here is the start of the function: int isDiv9(int a) { // function body goes here. }