1. Add and Subtract Decimals
Chapter 5
Add and Subtract Decimals

2. 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 to the hundredths place.
5.476 → 5.48 or 5.480

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

4. 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 – 52.7
75.93
23.23

5. Lesson 7 – Addition Properties
Commutative Property of Addition
The order in which the numbers are added does not change the sum.
Ex. – = 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