We can use grids and number lines to help us multiply decimals by whole numbers. Remember, multiplication is repeated addition.
Questions to Consider
Should my answer me larger or smaller than my divisor?
Between what two numbers should my product or quotient fall between?
Is my answer reasonable?
Can I use another strategy to check my work?
Strategies to Multiply Decimals
An area model can be used to multiply decimals by decimals. By decomposing each number by its place value, you can easily find partial products. Add the partial products to get your final product.
Below is another version of the area model. The partial products are the same as those shown in the model above.