Adding within 1,000
In 2nd grade, children learn to add within 1,000 by adding hundreds, tens, and ones separately; to make a new ten or hundred if needed; and to connect drawings or blocks to written steps.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our 2nd 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
What is the sum of 215 and 68?
- 283
- 273
- 383
Why this matters
Seeing that ten ones make a ten, and ten tens make a hundred, is what will make big numbers feel manageable for your child. It's the idea behind every trade your child makes when adding, so the steps make sense instead of feeling like rules to memorize. And it comes up for real, such as adding the points from two games or the people at two school events.
Once adding feels steady, subtracting within 1,000 comes next, using the same hundreds, tens, and ones.
Where kids can get stuck
- Writing each column's total straight into the answer, so 365 + 248 becomes 51013 instead of 613.
- Forgetting the new hundred made from the tens, so 271 + 154 comes out as 325 instead of 425.
- Lining the numbers up by their first digit, so 352 + 41 is added as 352 + 410 and gives 762.
How you can help
- Act out 156 + 127 with paper slips marked 100, 10, and 1. If the ones reach 13, trade 10 of them for a ten, and talk about where that new ten goes.
- Keep a running score across two rounds of a family game, like 184 points and then 237, and ask your child to explain each trade as they add the rounds together.
- Total the pages of two chapter books on the shelf, such as 176 and 148 pages, and ask how many pages your child would read by finishing both.
The kid-friendly video below explains it in a few minutes, and Bobby's Math Club offers free practice that grows with your child.
Kid-friendly explanation
Questions parents ask
Why is my child learning to add three-digit numbers with blocks and drawings?
Blocks and drawings show what happens when hundreds, tens, and ones are put together. Seeing ten tens become a hundred makes the trade clear. Children who understand this use written methods correctly and catch their own mistakes. The standard written method, with the numbers stacked in columns, is expected by the end of 4th grade, built on this understanding.
What does it mean to compose a ten or a hundred?
Composing means grouping ten of one unit into one of the next. If the ones in 365 + 248 add up to 13, your child groups 10 of them into a new ten, leaving 3 ones. Adults often call this carrying. If the tens then add up to more than 9, ten tens become a new hundred in the same way.
How can my child tell if a three-digit sum is right?
Estimating first is the quickest check. For 365 + 248, your child can notice that 365 is between 300 and 400, and 248 is between 200 and 300, so the answer should be between 500 and 700. Then 613 makes sense, and 51013 clearly does not. Adding in a different order, such as the ones first and then the hundreds, is another good check.
Make learning math fun
Bobby's Math Club turns 2nd grade math practice into something fun to do together.
- Unlimited free practice
- Practice that starts where your child is and grows with them
- Level-ups, badges, and a cheer for every win
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 2.NBT.B.7: “Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.” Learn how Bobby's Math Club can help your students grow. (Common Core 2.NBT.7)