What is the square root of 16?

The square root of 16 is 4. This is because 4 multiplied by itself (4 x 4) equals 16. It's also worth noting that -4 is also a square root of 16, since (-4) x (-4) = 16. However, when people refer to "the" square root, they typically mean the principal square root, which is the positive one (4).