Facts
When adding and subtracting decimals, it's important to line up the __________ in both numbers.
Decimal point or place value
Add these decimals. 21.74 + 8.27
30.01
3.2 × 4
12.8
Ignore the decimal: 32 × 4 = 128
Put back 1 decimal place → 12.8
Subtract these decimals.
3.53 - 2
1.53
6.8 ÷ 2
3.4
The divisor 2 is a whole number, so bring the decimal straight up into the answer.
2 goes into 6 → 3 (write 3). Remainder 0.
Bring down 8 (tenths place). 2 goes into 8 → 4.
You wrote the 4 in the tenths place → 3.4
the number you are dividing into is called ____________
Dividend
Ex: in 4.8 ÷ 4, 4.8
Add these decimals.
17 + 9.54
26.54
Multiply these decimals. 0.7 × 6
4.2
- Ignore the decimal 7 × 6 = 42
- 1 decimal place total → 4.2
Subtract these decimals.
2.15 - 1.05
1.1
4.8 ÷ 4
1.2
4 goes into 4 → 1
Bring decimal straight up
Bring down 8 (tenths): 4 goes into 8 → 2
→ 1.2
the number you are dividing by is called ______________
Divisor
ex: 4.8 ÷ 4, 4
Add these decimals. 6.125 + 18
24.125
Multiply these decimals.
1.5 × 3
4.5
Ignore the decimal 15 × 3 = 45
1 decimal place → 4.5
Subtract these decimals.
10.71 - 0.7
10.01
1.2 ÷ 3 = ___
0.4
Bring the decimal straight up.
3 into 1 → 0 (put 0 before the decimal).
3 into 12 tenths → 4 (write 4 after the decimal).
4×3=12; 12−12=0 → 0.4.
In the decimal 4.7, what place is the 7 in (the first spot to the right of the decimal point)?
In the tenths place.
Add these decimals. 4.67 + 29.1
33.77
Multiply these decimals
0.6 × 0.5
0.3
Subtract these decimals.
1.72 - 0.8
0.92
6.3 ÷ 3
2.1
Bring the decimal straight up.
3 into 6 → 2.
Bring down .3; 3 into 3 → 1.
Remainder 0 → 2.1
Write three tenths as a decimal.
What is 0.3?
Add these decimals.
5.2 + 3.11
8.31
Multiply these decimals. 2.5 × 0.4
1.00
Subtract these decimals.
2.54 - 1.82
0.72
2.7 ÷ 0.3
9
Move the decimal 1 place right in both numbers → 27 ÷ 3
Divide: 27 ÷ 3 =9