3-Digit Addition with Regrouping in Tens and Ones

So far, you've learned to add with regrouping in Ones and with regrouping in Tens.

But can we do both in one addition problem?

Yes, we can!

Let's try to do that by adding these numbers:

166 + 265 = ?

👉 Let's** expand the numbers** to see the value of each digit.

**166**

166 is 1 Hundred, 6 Tens, and 6 Ones.

**265**

265 is 2 Hundreds, 6 Tens, and 5 Ones.

Write the numbers in **column form** before you start adding.

Where should we start?

👉** First**, we add the** Ones**.

What is 6 + 5?

It's 11. This means we have 11 Ones.

Should we regroup?

Yes!

We **regroup the Ones** when the answer is more than 9, or if it has 2 digits.

We regroup 11 Ones by forming a Ten.

Now, we have 1 Ten and 1 One.

Add the 1 Ten to the Tens column.

Write 1 in the Ones place.

**Next**, add the **Tens.**

**👉** Remember, you added 1 more Ten to the Tens place when you regrouped the Ones. You need to also add that.

Let's add 1 + 6 + 6.

What is the sum?

It's 13.

Should we regroup?

Of course!

We **regroup the Tens** when the answer we get is more than 9, or has 2 digits.

Let's regroup 13 Tens by forming a Hundred.

Now, we have 1 Hundred and 3 Tens.

Write 3 in the Tens place, and **carry the 1 Hundred **to the Hundreds place.

**Finally**, add the **Hundreds.**

👉 Don't forget to add the 1 Hundred that we got from regrouping the Tens.

Can you add 1 + 1 + 2?

It's 4! We have 4 Hundreds.

Write 4 in the Hundreds place.

So, 166 + 265 equals **431**.

Great job! 🎉

Now, you can move on to practice.

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