Lesson 4: Multiply 2-Digit by 2-Digit Numbers

Property

When you multiply two 2-digit numbers, the four partial products you calculate correspond to the areas of the four smaller rectangles in an area model.
For factors decomposed as $(a+b)$ and $(c+d)$, the four partial products are $a \times c$, $a \times d$, $b \times c$, and $b \times d$.

Examples

Property

To multiply two-digit numbers, calculate two partial products.
The first is the top number multiplied by the ones digit of the bottom number.
The second is the top number multiplied by the tens digit of the bottom number, with a zero placed in the ones place to account for place value.
The final product is the sum of these two partial products.

Examples