Notes for Fractions and Decimals
Decimals · Addition & Subtraction: Line up the decimal points, then do the calculation.
Example: 57.4 - 4.23 Solution: 57.40 (don't forget to add the extra zero!)
- 4.23
53.17
· Multiplication: First do the calculation ignoring the decimals. Add up the number of decimal places in the original problem, and move over the answer's decimal point by that many places.
Example: 12.34 · 7.042
Solution: 1234 · 7042 is 8,689,828. We move the decimal 5 places to get 86.89828
· Division: Make the divisor (the outside number) easier by moving the decimal place.
Example: With 360 ÷ 0.009 we change the problem to 360,000÷9 (ans: 40,000)
Example: With 5400 ÷ 6000 we change the problem to 5.4 ÷ 6 (ans: 0.9)
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Labels: Decimals