Subtracting numbers up to a million
In 4th grade, children learn to subtract whole numbers up to a million on paper, such as 60,205 − 37,418, by lining up the places and regrouping, even across zeros.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our 4th grade practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Lina worked out 6,352 - 2,718 = 3,634. Which addition can she use to check her answer?
- 3,634 + 2,718
- 6,352 + 2,718
- 3,634 + 6,352
Why this matters
Subtracting big numbers with confidence lets your child answer the everyday questions that start with "how many more" and "how much is left." It comes before dividing larger numbers this year, which takes away a chunk at every step. In 5th grade, the same lined-up places help your child subtract decimals, such as 20 − 7.35. You’ll see it whenever you work out how much is left or how many more.
If trades between places trip your child up, adding numbers up to a million shows them in a slightly easier setting.
Where kids can get stuck
- Subtracting the smaller digit from the larger in each column, so 6,342 − 2,518 comes out as 4,236 instead of 3,824.
- Getting stuck subtracting across zeros, as in 5,000 − 2,346, and giving an answer like 3,346 instead of 2,654.
- Putting the smaller number on top because it came first in a story problem, writing 2,846 − 5,120 instead of 5,120 − 2,846.
How you can help
- Ask a savings question, like "A family trip costs 3,000 dollars and we have saved 1,865. How much more do we need?" Let your child explain each trade across the zeros out loud.
- Compare how many seats two stadiums hold, such as 68,500 and 41,922, and ask your child how many more the bigger one holds.
- Find the gap between two family birth years at the kitchen table, such as 1958 and 1987. Have your child subtract on paper and tell you which places needed a trade.
If it’s helpful, you can sign up for free, adaptive practice in Bobby's Math Club.
Questions parents ask
Why does my child cross out digits when subtracting?
Each crossed-out digit shows a trade between places. In 7,352 − 1,816, there aren’t enough ones to take away 6, so your child trades 1 of the 5 tens for 10 ones: the 5 becomes 4, and the 2 ones become 12. Writing each trade down keeps track of what every place really holds. That record is what makes the written method dependable, even with six-digit numbers.
My child keeps making mistakes with zeros in subtraction. How can I help?
Problems like 4,003 − 1,256 are hard because the regrouping has to travel across several places. Try asking your child to say what each trade means: one thousand becomes ten hundreds, one hundred becomes ten tens, one ten becomes ten ones. Practicing with play money, trading a large bill for smaller ones, can make those steps feel concrete.
What if adding big numbers goes well but subtracting them is harder?
That’s very common, and it isn’t a sign that anything is wrong. Subtracting asks for planning: before taking away, your child has to notice which places need a trade. Try having your child check each answer by adding it to the number taken away. Landing back on the starting number builds confidence.
Make learning math fun
Bobby's Math Club turns 4th grade math practice into something fun to do together.
- Unlimited free practice
- Practice that starts where your child is and grows with them
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
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Join the clubNote for teachers: This skill is covered by Common Core math standard 4.NBT.B.4: “Fluently add and subtract multi-digit whole numbers using the standard algorithm.” Learn how Bobby's Math Club can help your students grow. (Common Core 4.NBT.4)