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Step 2: Add the tens. H t O Addition of three 3-digit numbers

1 (carried over) + 5 + 6 = 12 tens 1 1 Adding three 3-digit numbers is the same as adding two 3-digit numbers.

Regroup 12 tens into 1 hundred and 2 tens. 2 5 4 Let us add 217 + 342 + 153. Arrange the numbers in the place value columns and follow
Write 2 in the tens place and carry over 1 hundred to the hundreds + 1 6 8 the given steps:

column. 2 2 Step 1: Add the ones. H t O
Step 3: Add the hundreds. H t O 7 + 2 + 3 = 12 ones = 1 ten + 2 ones. 1 1

1 (carried over) + 2 + 1 = 4 hundreds 1 1 Write 2 in the ones column and carry over 1 ten to the tens 2 1 7

Write 4 in the hundreds column. 2 5 4 column. 3 4 2

Thus, 254 + 168 = 422. + 1 6 8 Step 2: Add the tens. + 1 5 3
4 2 2 7 1 2
Addition of 3-digit numbers by regrouping hundreds 1 (carried over) + 1 + 4 + 5 = 11 tens = 1 hundred + 1 ten.
Write 1 in the tens column and carry over 1 hundred to the
When we have more than 9 hundreds, say 10 hundreds, we can regroup the 10 hundreds hundreds column.
into 1 thousand and 0 hundreds. Step 3: Add the hundreds.

1 (carried over) + 2 + 3 + 1 = 7 hundreds.
= Write 7 in the hundreds column.

10 hundreds 1 thousand Thus, 217 + 342 + 153 = 712.

Example 4: Add 765 and 389. Think Tank Logical Thinking
Solution: Write the numbers in the place value columns. 182
Step 1: Add the ones. H t O Find the missing numbers in the addition pyramid.
Hint: Each block (except the bottom row) has the sum of the
5 + 9 = 14 ones 1 two numbers below it. 20 26 48 22 18
Regroup 14 ones into 1 ten and 4 ones. 7 6 5

Write 4 in the ones column and carry over 1 to the tens column. + 3 8 9 practice time 2B
4

Step 2: Add the tens. H t O 1. Add the following. Identify which place values need regrouping.
1 (carried over) + 6 + 8 = 15 tens 1 1 (a) H t O (b) H t O (c) H t O

= 1 hundred and 5 tens. 7 6 5 7 0 9 5 2 3 7 8 5

Write 5 in the tens column and carry over 1 to the hundreds + 3 8 9 + 1 0 4 + 1 8 3 + 1 1 5
column. 5 4
Step 3: Add the hundreds. th H t O 2. Find the sum of the following.

1 (carried over) + 7 + 3 = 11 hundreds 1 1 1 (a) H t O (b) H t O (c) H t O
Regroup 11 hundreds into 1 thousand and 1 hundred. Write 1 in 7 6 5
2
5
3
the hundreds column and 1 thousand in the thousands column. + 3 8 9 + 3 4 7 + 3 4 9 + 2 5 8
7
6
4
0
3
5
Thus, 765 + 389 = 1154. 1 1 5 4
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