1. Adding, Subtracting, Multiplying, and Dividing Decimals

2. Adding Decimals Rules: Write number sentence vertically. Line up the decimals. Add extra zeroes to keep place value. Follow whole number addition rules. Bring the decimal straight down in the sum.

3. Example 3.275 + 5.6 3.275 +5.600 8.875

4. Example: 9 + 2.04 9.00 +2.04 11.04

5. Subtracting Decimals Rules: Write number sentence vertically. Line up the decimals. Add extra zeroes to keep place value. Follow whole number subtraction rules. Bring the decimal straight down in the difference.

6. Example 17.3 – 2.48 17.30 -2.48 14.82 210 6 12

7. Example 78 – 3.09 78.00 - 3.09 74.91 710 9

8. Multiplying Decimals Rules Write number sentence vertically. The number that has the most digits needs to be on top. Do not line up the decimals. Do not add zeroes. Multiply following whole number multiplication rules. Count how many digits are to the right of each decimal and add them together. Move the decimal over to the left that many spaces.

9. Example: 7.43 x 8.2 7.43 x 8.2 1486 +5944x 60.926 2 decimal places 1 decimal places 3 decimal places 1 1 2 3

10. Example: 9.1 x 3.855 3.855 x 9.1 3855 +34695x 35.0805 3 decimal places 1 decimal places 4 decimal places 11 4 4 7 1

11. Dividing Decimals Rules Write number sentence with the dividend in the “house” and the divisor on the “outside.” Move the decimal in the divisor over until it is written as a whole number. Move the decimal the same number of places over in the dividend. Add zeroes if needed. Move the decimal straight up. Divide following whole number division rules.

12. Example: 57.2 ÷ 0.04 0.04 57.2 45720 2 decimal places in 0.04 Move 2 decimal places to the right in the divisor and dividend. 1 -4 3 2 4 1 7 - 1 6 1 - 1 2 0 0 - 0 0

13. Example: 1,310.981 ÷ 13.3 13.3 1,310.981 133 13,109.81 1 decimal places in 13.3 Move 1 decimal place to the right in the divisor and dividend. - 1 1 9 7 1 1 3 9 - 1 0 6 4 7 5 8 - 6 6 5 9 3 1 9 8. 5 7 - 9 3 1 0

14. Now you try! Decimals can be found in your life. Today you are participating in the Metric Olympics. You can measure distance, weight, etc. very accurately using decimals. Now for our competition…use your scrap paper to answer the four decimal questions. The first one done with accurate answers is the winner!