Concatenating ints

I've spent hours trying to make this work... I guess I'm not asking google the right question.

int a = 5;
int b = 6;
int c = 7;

I need to make these a single int with the value 567.
I've tried going back and forth from char* and string* and I've tried atoi etc etc. They'd all give me either 18(sum), or 3 (the number of variables)

Any pointers?

multiply by powers of ten.

Simple case of overcomplication... I feel stupid xD

Thanks again AWOL