Square of 4 = 4^2 = 4 * 4 = 16
Incase you're not sure how squaring works:
4^2 = 4*4
4^3 = 4*4*4
4^4 = 4*4*4*4
4^5 = 4*4*4*4*4
The number in the exponent (the number after the ^ symbol) determines how many times the number (4) should be multiplied with itself.
