3-Digit Subtraction Games for Kids

How to Learn 3-Digit Subtraction

To subtract three-digit numbers, line them up by place and subtract from the right: ones, then tens, then hundreds. When a digit on top is too small, regroup from the place to its left. Every step is a small fact, like 13 − 7 inside 523 − 167, so the subtraction facts within 20 need to be quick first.

Hundreds, tens and ones

Every three-digit number is made of hundreds, tens and ones: 586 is 5 hundreds, 8 tens and 6 ones. Take each place from the same place: 500 − 200 = 300, 80 − 30 = 50 and 6 − 4 = 2, so 586 − 234 = 352. When every digit on top is at least as big as the one below it, no regrouping is needed.

Take away hundreds and tens in your head

When that place has enough, taking away whole hundreds or tens changes only that place: 700 − 300 = 400, 650 − 30 = 620 and 456 − 100 = 356. When it does not, a hundred is broken and the hundreds digit goes down too: in 320 − 50, 2 tens are too few for 5, so the answer is 270, and 10 less than 305 is 295, because there are no tens to take from. Finding 10 less or 100 less without writing is a 2nd grade goal, and the table below shows how.

Regrouping twice: 523 − 167

When the ones and then the tens run short, regroup twice, one place at a time:

1. Ones: 3 is smaller than 7, so break 1 ten into 10 ones. The 3 ones become 13 and the 2 tens become 1 ten. 13 − 7 = 6.
2. Tens: 1 is smaller than 6, so break 1 hundred into 10 tens. The 1 ten becomes 11 tens and the 5 hundreds become 4. 11 − 6 = 5.
3. Hundreds: 4 − 1 = 3. The answer is 356.

Subtracting across zeros

When the place you need to regroup from has a zero in the top number, there is nothing to take there, so go one place further. In 400 − 163, the ones need regrouping but there are no tens. Break a hundred into 10 tens, then break one of those tens into 10 ones: 400 becomes 3 hundreds, 9 tens and 10 ones. Now every place works: 10 − 3 = 7, 9 − 6 = 3 and 3 − 1 = 2, so 400 − 163 = 237.

Check the answer

Estimate first: 523 − 167 is close to 520 − 170 = 350, so an answer near 350 makes sense and 444 does not. Then add back: 356 + 167 = 523, the number you started with, so 356 is right.

Common mistakes

• 444 for 523 − 167. Your child took the smaller digit from the bigger one in each place: 7 − 3 = 4, 6 − 2 = 4 and 5 − 1 = 4. The places with too few were swapped instead of regrouped.
• 466 for 523 − 167. Your child regrouped each place but never lowered the place they took from: 13 − 7 = 6, 12 − 6 = 6 and 5 − 1 = 4. Adding back catches it: 466 + 167 = 633, not 523.
• 363 for 400 − 163. Your child took 0 from 3 and 0 from 6 instead of regrouping: 3 − 0 = 3, 6 − 0 = 6 and 4 − 1 = 3. A zero on top means regrouping across it only when a place has too few, like the 0 ones here with 3 to take away; in 405 − 102 every place has enough, and the zero stays.

The online games on this page put both slips among the answers: for 523 − 167, your child sees 444 and 466 next to 356 and learns to tell them apart.

The same place value steps work for addition: to see how a new ten or hundred is made, try our 2-digit addition games. For why your child's homework splits numbers into hundreds, tens and ones, see expanded form in our guide to new math.

What Grade Learns 3-Digit Subtraction?

Three-digit subtraction is a 2nd and 3rd grade skill in the US, usually at ages 7-9. Common Core standard 2.NBT.B.7 asks 2nd graders to subtract within 1,000 using models, drawings and strategies based on place value, understanding that it is sometimes necessary to break a ten or a hundred. Standard 2.NBT.B.8 asks them to subtract 10 or 100 from a number between 100 and 900 in their head, and 2.NBT.B.9 to explain why their strategies work. Standard 3.NBT.A.2 asks 3rd graders to subtract within 1,000 fluently.

In England, Year 3 children subtract numbers with up to three digits using the formal written method of columnar subtraction, subtract ones, tens and hundreds from a three-digit number in their head, and find 10 or 100 less than a given number.

Age

7-9

US grade

Grades 2-3

Standard

Common Core 2.NBT.B.7, 3.NBT.A.2

England

Year 3