Question

Write down the converse and contrapositive of the following:

If a positive integer n is divisible by 9, then the sum of its digits is divisible by 9.

Answer 1

Converse If the sum of the digits of a positive integer n is divisible by 9, then it is divisible by 9.

Contrapositive If the sum of the digits of a positive integer n is not divisible by 9, then it is not divisible by 9.