22
Adding and Subtracting Whole Numbers
and Decimals
Whole numbers are numbers with no fractional or decimal portion. Decimals are numbers with
digits to the right of the decimal point. To add a positive number, move to the right on the number line.
To subtract a positive number, move to the left on the number line.
Skills Workshop 6
When adding or subtracting whole numbers and decimals, place each number in a vertical list,
aligning the decimal points. Then, complete the operation starting with the place farthest to the right
and working to the left. In an addition operation, carry the remainder to the top of the next column
to the left. The result of addition is called the sum. In a subtraction operation, borrow from the next
column to the left when needed. The result of subtraction is called the diff erence.
See It
Find the sum of these numbers: 65.9, 88.7, and 12.
Step 1: Place the three numbers in a vertical list, aligning the decimal points.
Step 2: Add the tenths column (16) and carry the remainder (1).
Step 3: Add the ones column (16) and carry the remainder (1).
Step 4: Add the tens column (16). The sum is 166.6.
Check It
1. 5.87 + 4.956 + 2.011 + 4 =
2. 112,058 – 98,968 =
3. 112.058 + 2.1 + 93.237 =
4. 67,058.45 – 102,450.04 =
0 5
Adding Positive Numbers
10 15 20
Adding Negative Numbers
10
7
685
71.5
+ 18.65
775.15
29
56
+ 17
102
98
23.3
– 54
20.7
2 1 1 1