Is there a word describing the first number in a multiplication?

Solution 1:

Depending on how one interprets the vertical notation (is that twelve times four or four times twelve?) it can be either the multiplier or the multiplicand; and the solution is termed the product.

Solution 2:

I would call it the first factor. In this particular example, we have two factors (4 and 12). Their product being 48.

Solution 3:

It's the multiplier.

The vertical format can only be considered equivalent to 4 × 12 because while multiplication is commutative and hence 4 × 12 is the same as 12 × 4, subtraction is not and when writing the subtraction 12 - 4 in vertical form we put the 4 at the bottom.

Hence the top number in this format must be considered the multiplier, and the second must be considered the multiplicand.