Addition within 1,000: Regrouping Ones to Tens

Free sample questions, a clear explanation, and 5 practice skills with an AI tutor that guides without giving the answer away.

Level Up! The Awesome Power of Regrouping!

Hey Math Explorer! Have you ever played with LEGOs and had so many small single blocks that you decided to trade 10 of them for one of those long ten-block sticks? Guess what? You were already regrouping! In math, when we have too many ones in the ones place, we do the exact same thing: we bundle up 10 ones and trade them for 1 ten. It’s like leveling up your numbers!

Let's imagine we're adding 127 + 316.

First, we look at the ONES. We have 7 ones and we add 6 more ones. That's 13 ones! Whoa!
Time to regroup! The ones place can only hold one digit (up to 9). So, we take 10 of those 13 ones and swoosh!—we trade them for 1 new ten-rod. We have 3 single ones left over.
Next, we add the TENS. We had 2 tens and 1 ten, PLUS our brand new ten from regrouping. That's 2 + 1 + 1 = 4 tens.
Finally, the HUNDREDS. 1 hundred + 3 hundreds = 4 hundreds.

So, 127 + 316 = 443. See? You just leveled up your addition skills!

Key Takeaway!

When the ones column adds up to 10 or more, it's a signal to regroup! Just bundle up a group of 10 ones and move it over to the tens place as 1 new ten.

Solving a Yummy Problem!

A baker has 238 cookies and bakes 145 more. How would you explain to a friend how to find the total, focusing on the 'extra' ones?

You could say this to your friend:

"Okay, let's figure out this cookie mountain! First, let's just look at the single cookies, the ones. The baker has 8 single cookies (from 238) and bakes 5 more single cookies (from 145). If we add them, 8 + 5 is 13. That's more than a box of ten can hold!

So, let's take 10 of those ‘extra’ cookies and pack them into a new box of ten. Now we only have 3 single cookies left over. That new box of ten joins the other tens. So when we add the tens, we have to remember our new box! It's 3 tens + 4 tens + our 1 new ten. Easy peasy!"

Sample questions

1. What is 36 + 27?

✓ 63

○ 513

○ 53

○ 60

Answer: 63 — Add the ones first. If you have 10 or more ones, make a new ten and add it to the tens column.

2. If you have 48 blocks and get 15 more blocks, how many blocks do you have in total?

○ 53

✓ 63

○ 513

○ 60

Answer: 63 — Count all the ones blocks together. Can you make a new group of ten? Don't forget to add it to the tens!

3. Look at the problem: 54 + 29. When you add the ones, you get 13 ones. What is the next step?

○ Write 13 in the ones place.

○ Write 3 in the ones place and carry 1 to the hundreds place.

○ Write 1 in the ones place and carry 3 to the tens place.

✓ Write 3 in the ones place and carry 1 to the tens place.

Answer: Write 3 in the ones place and carry 1 to the tens place. — When you have more than 9 ones, you regroup. How many ones are left, and where does the new ten go?

Skills in this topic

Add two numbers with regrouping ones to tens using concrete base-ten blocks.
Represent addition with regrouping ones to tens using pictorial models (e.g., drawing blocks, place value charts).
Add two 3-digit numbers with regrouping ones to tens using the standard algorithm.
Solve addition word problems involving regrouping ones to tens using bar models.
A baker has 238 cookies and bakes 145 more. How would you explain to a friend how to find the total number of cookies, focusing on the 'extra' ones?

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