Teen numbers as ten and some more
In kindergarten, children learn that the numbers 11 to 19 are made of ten ones and some more ones, such as 18 = 10 + 8.
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
What do 10 and 1 make?
- 10
- 11
- 12
Why this matters
This is your child's first step into place value: the 1 in 14 stands for ten, not one. In 1st grade they will treat ten ones as a single ten and work with numbers like 47 as tens and ones, and in 2nd grade with hundreds. Without this idea, adding 26 + 10 or carrying a ten later on can feel like a mystery.
Where kids can get stuck
- Thinking the 1 in 16 means one object, so they show 16 with 1 block and 6 blocks.
- Losing count while building the ten, so the group of ten ends up holding 9 or 11 objects.
- Writing 13 = 10 + 3 but not 10 + 3 = 13, or not linking the equation to the objects.
How you can help
- Count 15 crackers by first filling an egg carton cut to ten spaces, then putting the extra crackers beside it, and say "ten and five more is 15."
- Use your ten fingers plus some of your child's fingers to show teen numbers, such as your ten and their three for 13.
- Bundle 10 straws with a rubber band and keep loose straws nearby, then build teen numbers together, saying each one as ten and some more.
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 that 18 is 10 and 8?
Seeing teen numbers as ten and some more is the first step in place value. It explains why 18 is written with a 1 and an 8: the 1 stands for one group of ten, and the 8 stands for eight extra ones. This makes larger numbers and adding much easier to understand in later grades.
My child thinks the 1 in 15 means one. How can I help?
This is a very common confusion. Build the number with objects: count out ten in a row and five more beside it. Then point to the 1 in 15 and say, "This means this group of ten." Seeing the ten and the extra ones together, many times, helps the written number make sense.
What does this lead to in 1st grade?
In 1st grade, children learn that ten ones can be thought of as one ten, and they use this to understand two-digit numbers up to 99. For example, 47 is four tens and seven ones. This understanding supports adding and subtracting larger numbers in later grades.
Make learning math fun
Bobby's Math Club turns kindergarten math practice into something fun to do together.
- Unlimited free practice
- Questions matched to your child’s level, a few minutes a day
- 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.NBT.A.1: “Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.” Learn how Bobby's Math Club can help your students grow. (Common Core K.NBT.1)