SME
Grade 6 Math · Problem type
Add and subtract decimals
Use this for “$18.25 − $6.40,” or 9.3 − 4.56.
Chart
First number
ones
4
.
tenths
7
hundredths
4
thousandths
0
+ Second number
4
.
5
6
0
Sum
9
.
3
0
0
4.74 + 4.56 = 9.3.
The points line up: tenths under tenths, hundredths under hundredths.
This is an example. Type your own values to start a new problem.
First number
calculated
Second number
example
Sum
example
Formulas
4.74 + 4.56 = 9.3
First number + second number = sum
Assumptions
•
Line up the decimal points, so tenths are under tenths and hundredths under hundredths.
•
Write zeros in empty places: 9.3 − 4.56 is 9.30 − 4.56. A whole number like 12 has its point after the ones.
•
Numbers to 9,999.999 (three decimal places).
Step-by-step
WE KNOW
Sum: 9.3
Second number: 4.56
FIND
first number
Step 1 · Find first number
? + 4.56 = 9.3
First number + second number = sum
Subtract: line up the points, write zeros in empty places, and regroup where needed.
First number = 9.3 − 4.56
8
12
10
9
.
3
0
−
4
.
5
6
4
.
7
4
First number = 4.74
Check
Put the numbers back in. Both sides should match.
4.74 + 4.56 = 9.3 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
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Related lessons
Compute with multi-digit numbers and decimals
Main lesson
Divide multi-digit numbers with a remainder
Use this for “1,431 ÷ 99 = ?” when it doesn’t come out even: 14 remainder 45.
Multiply decimals
Use this for “Find the value of (0.052)(0.36),” or 2.35 × 1.4.
Divide by a decimal
Use this for “3.6 ÷ 1.2”: make the divisor whole, then divide.