Adding and Subtracting Decimals

Adding and Subtracting Decimals

Adding and Subtracting Decimals

When adding and subtracting decimals, first line up the decimals. We have 4 and 23 hundredths, plus 9 and 75 thousandths. Same with subtraction. 5 and 629 thousandths, minus 45 hundredths. Then if you have any empty spaces you can fill in with zeros.

Adding zeros to the back of your number, to the back of a decimal, doesn’t change the value of your number. These numbers are still what they were, they’re still equal. Then we just add or subtract like we usually would. 0 plus 5 is 5, 3 plus 7 is 10.

Write your zero, carry your 1. 1 plus 2 is 3, plus 0 is 3. Bring that decimal down, 4 plus 9 is 13. Our answer, or our sum, is 13 and 305 thousandths. Now for subtraction. We’re going to do the same thing except now we are subtracting.

9 minus 0 is 9. 2 minus 5, we can’t take 5 from 2 so we need to borrow from our 6, just like we usually would, and add a 1 onto our 2 which makes 12. 12 minus 5 is 7, then 5 minus 4 is 1, we bring our decimal down and 5 minus 0 is 5. Our result, or our difference, is 5 and 179 thousandths.

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by Mometrix Test Preparation | Last Updated: June 10, 2019