Splitting numbers up to 10 into two parts
In kindergarten, children learn to break numbers up to 10 into two parts in more than one way, such as 5 = 2 + 3 and 5 = 4 + 1.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our kindergarten 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
There are 5 ladybugs in total. Some are on a leaf and the rest are on a flower. If 2 ladybugs are on the leaf, how many ladybugs are on the flower?
- 2
- 3
- 4
Why this matters
Seeing that 7 can be 5 and 2, or 4 and 3, gives your child flexible ways to add and subtract instead of counting every time. It lets them use facts they know to work out ones they don't, such as solving 8 + 6 as 8 + 2 + 4 in 1st grade. Breaking numbers apart also helps with adding two-digit numbers in 2nd grade and, later, with multiplying larger numbers.
Where kids can get stuck
- Finding one way to split a number, such as 5 = 4 + 1, and believing it is the only answer.
- Thinking 6 = 4 + 2 is wrong because they expect the answer to come after the equal sign.
- Losing or adding an object while splitting 8, ending with 5 and 4, and not checking the parts still make 8.
How you can help
- Give your child 7 grapes and two small plates, and ask how many different ways they can share the grapes between the plates, counting each time.
- Hold up 6 fingers using both hands and ask your child to find another way to show 6, such as 5 and 1 or 3 and 3.
- Hide some of 8 buttons under a cup and show the rest, then ask how many are hiding, talking about how the two parts make 8.
Want a little more? Watch the kid-friendly video below together, or try Bobby's Math Club for free practice that adapts to your child.
Kid-friendly explanation
Questions parents ask
Why is my child learning to split numbers into parts?
Knowing that 7 can be made of 5 and 2, or 4 and 3, helps your child see how numbers are built. That flexibility makes adding and subtracting easier, because your child can break numbers into friendlier parts. It is the groundwork for strategies such as making ten, which children use in 1st and 2nd grade.
Why does the equation sometimes start with the total, like 5 = 2 + 3?
Writing the total first shows that the equal sign means "the same as," not "the answer comes next." Children who only see equations like 2 + 3 = 5 often think the equal sign means "now write the answer." Seeing it both ways builds a truer understanding, which matters later in algebra and when solving problems with missing numbers.
How many ways should my child find to split a number?
The goal is to find more than one way, and many children enjoy finding them all. For 5, the pairs are 0 and 5, 1 and 4, 2 and 3, and the same pairs switched around. Your child does not need to list them all, but noticing that there are several ways is the main idea.
Make learning math fun
Bobby's Math Club turns kindergarten math practice into something fun to do together.
- Free, unlimited practice for every child in your family
- A few minutes a day, at just the right level
- 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 K.OA.A.3: “Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or equation (e.g., 5 = 2 + 3 and 5 = 4 + 1).” Learn how Bobby's Math Club can help your students grow. (Common Core K.OA.3)