Add and Subtract Decimals Chapter 5 Add and Subtract Decimals

Lesson 1 – Round Decimals Underline the digit in the place to which you want to round. Look at the digit to the right and use the rules for rounding. (0,1,2,3,4 → keep the digit; 5,6,7,8,9 → go up to the next digit) Either drop the remaining digits or change them to zeros. Example: Round 5.476 to the hundredths place. 5.476 → 5.48 or 5.480

Lesson 2 – Estimate Sums and Differences Round to either the ones place or the tens place. Example: Estimate 42.3 + 57.9 42.3 → 42 or 42.3 → 40 + 57.9 →+58 + 57.9 →+60 100 100

Lessons 6 & 10 – Adding and Subtracting Decimals Write the problem vertically. Make sure you line up the decimals. You can add zeros to any blank spaces. Add or subtract. Example: Find 75.93 – 52.7 75.93 - 52.70 23.23

Lesson 7 – Addition Properties Commutative Property of Addition The order in which the numbers are added does not change the sum. Ex. – 5 + 4 = 4 + 5 Associative Property of Addition The way in which the numbers are grouped does not change the sum. Ex. – (7 + 3) + 9 = 7 + (3 + 9) Identity Property of Addition The sum of any number and 0 equals the number. Ex. - 12 + 0 = 12