SME
Grade 2 Math · Problem type
Subtract three-digit numbers
Use this for “Find the value of 752 − 386.”
Picture
Trade 1 hundred for 10 tens, then 1 ten for 10 ones.
Cross out 1 hundred, 7 tens, 8 ones.
403 − 178 = 225
Flats are hundreds, rods are tens, small cubes are ones.
Take away: 178
Left: 225
This is an example. Type the numbers from your problem to start.
Start
−
Take away
=
Left
Number sentences
403 − 178 = 225
Good to know
•
Take ones from ones, tens from tens, hundreds from hundreds.
•
Not enough ones? Trade 1 ten for 10 ones. No tens? Trade 1 hundred for 10 tens first.
Step-by-step
WE KNOW
Start: 403
Take away: 178
FIND
left
Step 1 · Find left
403 − 178 = ?
Line up the places. Trade when a place has too few, then take away.
3
9
13
4
0
3
−
1
7
8
2
2
5
No tens to trade: trade 1 hundred for 10 tens
Trade 1 ten for 10 ones: 13 ones
Ones: 13 − 8 = 5
Tens: 9 − 7 = 2
Hundreds: 3 − 1 = 2
Left: 225
Check
Put the numbers back in. Both sides should match.
403 − 178 = 225 ✓
Topic check
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