Addition with Carrying
Crossing Tens
Sometimes when we add, the ones become too many. What happens then? Ten ones become one ten! Let's discover this together.
Riya's Collection! 📦
Riya is collecting stickers from different places.
She has 28 stickers in one box
and 15 stickers in another.
When she puts all the ones together, something new happens...
Milo notices: "There are too many ones — they turn into a ten!"
Remember This?
Addition without carrying
First, let's add where the ones stay below 10. Nothing changes place!
💡 Notice: 2 ones + 5 ones = 7 ones. Seven is less than 10, so nothing special happens. The ones just stay as ones!
When Ones Become Too Many
The discovery moment!
Now let's try 28 + 15. Watch what happens to the ones!
💡 Key Moment: When we add the ones and get more than 9, we have a problem! The ones place can only hold digits 0-9. What do we do with the extra ones?
Making a New Ten!
The carry moment
When we have 13 ones, 10 of them become 1 new ten!
We have 13 ones. Let's bundle 10 of them!
💡 Remember: "Ten ones make one ten." We're not moving a magic "1" — we're moving a real bundle of 10!
Adding the Tens
Including the new ten
For 28 + 15, we now add the tens. Don't forget the new bundle!
2 tens + 1 ten + 1 new ten = 4 tens
28 + 15 = 43
4 tens and 3 ones
💡 See the answer: We can see the answer before writing it! 4 bundles of ten and 3 loose ones make 43.
Writing the Addition
The vertical format
Now let's write it down step by step. Watch the carried ten!
⚠️ Important: We carry a ten, not "a one"! The small digit we write above is worth 10, because it represents 1 bundle of ten.
Fix Milo's Mistakes!
Learn from errors
Milo made some mistakes. Can you spot them and fix them?
Milo tried 27 + 15. He carried the 3 instead of the 1!
Milo tried 38 + 14. He forgot to add the carried ten!
Milo tried 46 + 17. He added the carry to both columns!
💡 Tip: When you carry, always ask yourself: "Did I add the new ten to the tens column, and only to the tens column?"
Practice Time!
Try some problems
💡 Strategy: First add the ones. If the sum is 10 or more, remember to carry!
Chapter Quiz
10 questions
This certifies that
Math Explorer
successfully completed
Chapter 5: Addition with Carrying
Real World Carrying
See it everywhere!
Carrying happens naturally in real life! Can you think of examples?
Examples Found: 0/6
💡 Key Insight: Carrying is natural, not artificial! Whenever you collect 10 of something, it's natural to group them together into a bigger unit.
Questions & Answers
Crossing over ten
Why do the ones sometimes overflow?
Because the ones place only holds nine. When you reach ten loose ones, they must become one bundle. The box is full, so it moves up.
What really happens when we carry?
Ten ones become one ten and move to the tens place. Nothing is created and nothing is lost. The same amount is just repacked.
What do I do with 27 plus 15?
Ones first. 7 and 5 make 12. Twelve is one ten and two ones. Write 2 in the ones and move the new ten up. Then 2 plus 1 plus the new ten is 4 tens. Answer 42.
Why is the leftover digit written below?
Because those are the ones that did not form a full bundle. Only complete tens move up. The loose ones stay behind.
Can the tens overflow too?
Yes. Ten tens make one hundred. The same rule works at every place, all the way up.
Why not just count on my fingers?
Fingers work for small numbers. Regrouping works for any number, however big. It is the rule that keeps working.
How can I picture it?
Think of an egg tray that holds ten. When the tray fills, you carry the whole tray to the shelf of tens. Loose eggs stay on the table.
How do I check my answer?
Estimate first. 27 plus 15 is near 30 plus 15, so about 45. If your answer is far from that, look again.
If a child says "carry the 1" without understanding that it represents a bundle of 10, they're performing magic, not math. This chapter ensures children see the transformation — 10 ones physically becoming 1 ten — before using any notation.
The goal: When a child writes a small "1" above the tens column, they should mentally picture a bundle of 10 items moving from one place to another.
❌ Not mental math tricks
❌ Not exam drilling
This chapter protects the child's number sense. Speed comes later, understanding comes first.