If a number is multiplied by itself, what is this operation called?

When a number is multiplied by itself, the operation is referred to as "squared." This term arises from the area calculation of a square, where each side of the square has a length of the same number. For example, if you take the number 3 and square it, you calculate 3 × 3, which equals 9. This reflects the geometric interpretation of squaring a number as calculating the area of a square.

The other options represent different mathematical operations. "Cubed" refers to multiplying a number by itself twice more (total of three times), which is not the case here. "Doubled" pertains to multiplying a number by 2, and "rooted" typically refers to the operation of finding a square root or cube root, which is unrelated to multiplying the number by itself. Thus, "squared" accurately describes the operation where a number is multiplied by itself.