SME
Grade 3 Math · Problem type
Subtract three-digit numbers with zeros
Use this for “Find the value of 400 − 162” or “503 − 207.”
Diagram
Flats are hundreds, rods are tens, small cubes are ones.
Take away: 162
Left: 238
This is an example. Type your own values to start a new problem.
Start
−
Take away
=
Left
Formulas
400 − 162 = 238
Start − take away = left
Assumptions
•
No ones and no tens to trade? Trade 1 hundred for 10 tens first.
•
Then trade 1 of those tens for 10 ones. Now every place has enough.
•
Check by adding back what you took away.
Step-by-step
WE KNOW
Start: 400
Take away: 162
FIND
left
Step 1 · Find left
400 − 162 = ?
Start − take away = left
Trade across the zeros, then take away each place.
3
9
10
4
0
0
−
1
6
2
2
3
8
No tens to trade: trade 1 hundred for 10 tens
Trade 1 ten for 10 ones: 10 ones
Ones: 10 − 2 = 8
Tens: 9 − 6 = 3
Hundreds: 3 − 1 = 2
Left = 238
Check
Put the numbers back in. Both sides should match.
400 − 162 = 238 ✓
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Fluently add and subtract within 1,000
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Addition and subtraction word problems within 1,000
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