Concatenation of ints using math only

intconcat.java

public class Test {
	public static void main(String[] args) {
		System.out.println(concat(12, 34));
	}
	public static int concat(int a, int b) {
		if (b == 0) return a*10;
		return a*pow(10,len(b)) + b;
	}
	public static int pow (int a, int b) {
		if (b == 0) return 1;
		int p = 1;
		for (int i = 0; i < b; i++) {
			p *= a;
		}
		return p;
	}
	
	public static int len(int n) {
		if (n == 0) return 0;
		if (n < 0) n = -n;
		int i = 0;
		while (n > 0) {
			i++;
			n /= 10;
		}
		return i;
	}
}