To multiply integers with decimals, you can follow a simple three-step process: ignore the decimal point, perform the multiplication, and then correctly place the decimal point in the product.
Steps to Multiply Integers with Decimals
Here's a breakdown of the process with examples:
-
Ignore the Decimal Point: Treat the decimal number as a whole number by temporarily removing the decimal point.
-
Multiply the Numbers: Multiply the integer and the "whole number" version of the decimal using standard multiplication techniques.
-
Place the Decimal Point: Count the number of decimal places in the original decimal number. Then, in your product, count from right to left the same number of decimal places and insert the decimal point.
Examples
Let's illustrate this with a few examples:
Example 1: 3 x 2.5
- Step 1: Ignore the decimal: Consider 2.5 as 25.
- Step 2: Multiply: 3 x 25 = 75
- Step 3: Place the decimal: 2.5 has one decimal place. So, 75 becomes 7.5
Therefore, 3 x 2.5 = 7.5
Example 2: 12 x 0.15
- Step 1: Ignore the decimal: Consider 0.15 as 15.
- Step 2: Multiply: 12 x 15 = 180
- Step 3: Place the decimal: 0.15 has two decimal places. So, 180 becomes 1.80
Therefore, 12 x 0.15 = 1.80 (or 1.8)
Example 3: 5 x 1.75
- Step 1: Ignore the decimal: Consider 1.75 as 175
- Step 2: Multiply: 5 x 175 = 875
- Step 3: Place the decimal: 1.75 has two decimal places. So, 875 becomes 8.75
Therefore, 5 x 1.75 = 8.75
Summary
Multiplying integers with decimals is straightforward. By ignoring the decimal during the multiplication process and then correctly placing it in the final product, you can easily arrive at the correct answer. Remember to count the decimal places in the original decimal number to determine the placement in the product.
