Multiplication is almost like a complex form of addition. For example, 5x3 is like adding three to itself five times (3+3+3+3+3). This formula can work for small numbers, but 215x3 is too large to work this way.

Rewrite the problem so that it is aligned vertically and the numbers are stacked on top of each other. The ones column should line up, as should the tens, hundreds, etc.

Multiply the ones column together (5x3=15). Write the ones digit from the product (5) below the product line and carry the tens digit (1) above the tens column.

From here, multiply every other digit in the top line with the ones digit on the line below starting from right to left (tens, hundreds, etc). In this case, since we have the 1 that was carried over, you need to multiply 3 and 1, then ADD the additional 1 that was carried over (3x1+1=4).

Write each product below the product line, carrying over as needed until you have multiplied the ones digit to every number in the top line (2x3=6).

1. Any time you multiply a number by one, you get that same number back again. For example, three times one is three.
2. If you multiply a number by zero, you will always get zero.
3. You may see multiplication problems expressed in different forms. Sometimes there's an x, other times there's a dot or an asterisk and parentheses that mean to multiply as well.