What do you call the second number to a multiplication problem?

Answer 1

Each of the numbers that are multiplied is called a factor. Multiplicand x Multiplier = Product. I think Multiplier is the answer that you're looking for. I think these terms are kind of outdated, but I think they came from the way of thinking about multiplication as repetitive addition. So the Multiplicand is the number that you're going to add up, and the Multiplier tells you how many times to add it up.

So 5 x 3, where 5 is Multiplicand and 3 is Multiplier, you would add 5, three times:

5 + 5 + 5 = 15, where 3 x 5, you would add 3, five times: 3 + 3 + 3 + 3 + 3 = 15