Adding up to four two-digit numbers
In 2nd grade, children learn to add up to four two-digit numbers, such as 23 + 45 + 17 + 30, using place value and smart grouping.
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 5 + 5 + 5 + 5 + 5?
- 20
- 25
- 30
Why this matters
Totaling a list of numbers is math your child will use constantly: scores from several rounds, prices on a shopping trip, or minutes read across a week. Keeping every number in view and spotting pairs that make a ten builds organization and flexibility. They will need both for adding larger numbers and solving multi-step problems in 3rd grade and beyond.
Where kids can get stuck
- Leaving out one of the numbers partway through, especially with four, so the total comes out short.
- Forgetting to regroup when the ones make more than 9, writing all of 15 in the ones place.
- Adding strictly left to right and missing easy pairs, such as 36 and 14 making a friendly 50.
How you can help
- Add up the cost of three or four items on a grocery receipt with prices under a dollar, and ask your child which two prices are easiest to add first.
- Total the points in a game with several rounds, such as 25, 18, 32, and 15, and ask your child to group numbers that make tens before adding.
- Count everyone's steps, laps, or jumping jacks after a family exercise break and add the four totals together, talking through how each person grouped them.
If it’s helpful, you can watch the kid-friendly video below, or sign up for free, adaptive practice in Bobby's Math Club.
Kid-friendly explanation
Questions parents ask
Why is my child learning to add several numbers by grouping them?
Grouping numbers to make tens, such as pairing 26 and 14 to make 40, turns a long problem into simpler steps. It shows your child that numbers can be added in any order. This flexible thinking reduces mistakes and builds mental math skills that help with larger numbers and multi-step problems.
How can my child keep track of four numbers without losing one?
Encourage your child to cross out or tick each number as it is used, or to write each partial total as they go. Grouping numbers into pairs first also helps, because then there are only two totals left to combine. Keeping work neat and in order is part of what this skill teaches.
Is it okay if my child adds the tens first?
Yes. Adding all the tens, then all the ones, then combining them is a strong strategy based on place value. For 34 + 21 + 15, that is 30 + 20 + 10 = 60 and 4 + 1 + 5 = 10, so the total is 70. It is different from the column method adults may know, but it is mathematically sound.
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.6: “Add up to four two-digit numbers using strategies based on place value and properties of operations.” Learn how Bobby's Math Club can help your students grow. (Common Core 2.NBT.6)