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regrouping tens and ones

Example 4. Add 254 and 168.
Solution. Write the numbers in columns and add them.

Step 1. Add the ones and regroup. Step 2. Add the tens and regroup.

H T O H T O

1 1 1
2 5 4 2 5 4

+ 1 6 8 + 1 6 8

2 2 2

4 + 8 = 12 ones = 1 ten 2 ones 1 + 5 + 6 = 12 tens = 1 hundred 2 tens

Write 2 in the ones place and carry Write 2 in the tens place and carry
over 1 to the tens column. over 1 to the hundreds column.

Step 3. Add the hundreds.
H T O
1 + 2 + 1 = 4 hundreds
1 1
Write 4 in the hundreds place.
Therefore, 254 + 168 = 422. 2 5 4
+ 1 6 8

4 2 2

regrouping Hundreds

When we have more than 9 hundreds, we can regroup 10 hundreds into 1 thousand.

a. 10 hundreds = 1 thousand

b. 12 hundreds = 1 thousand 2 hundreds

Example 5. Add 765 and 389.

Solution. Write the numbers in columns and add them.
Th H T O
Step 1. Add the ones and regroup.
1
5 + 9 = 14 ones
7 6 5
= 1 ten 4 ones
+ 3 8 9
Write 4 in the ones place and carry over 1 to the tens column.
4

42 Mathematics 3