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2. Find the sum by expanding the addends.

(a) 217 + 562 (b) 481 + 318 (c) 645 + 152
(d) 516 + 273 (e) 424 + 263 (f) 385 + 512

Addition of 3-digit numbers with regrouping

Addition of 3-digit numbers by regrouping ones

When we have more than 9 ones, say 12 ones, we can regroup 12 ones into 1 ten and 2
ones. For example:

Similarly, 2 tens and 16 ones can be regrouped
as 3 tens and 6 ones as shown below.

1 ten 12 ones 2 tens 2 ones 2 tens 16 ones 3 tens 6 ones

Rohit’s father runs a bakery.
He got an order of 629 pineapple pastries and 353 chocolate pastries.

Rohit: How many pastries do you need to make in all?

Father: 982 pastries in all.

Rohit: How did you get this number?
Father: By adding 629 and 353.

Let us learn how Rohit’s father added 629 and 353.

Write the numbers in the place value columns.
Step 1: Add the ones. H t O

9 + 3 = 12 ones 1
Regroup 12 ones into 1 ten and 2 ones. 6 2 9

Write 2 in the ones column and carry over 1 ten to the tens + 3 5 3
column. 2

Step 2: Add the tens. H t O
1 (carried over) + 2 + 5 = 8 tens 1

Write 8 in the tens column. 6 2 9
+ 3 5 3
8 2

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