Page 42 - Touchpad Mathematics_Ver1.0_C4

Addition oF 3-digit numBErS

Addition without regrouping
Example 1. Add 271 + 325.

Solution. Write the numbers in columns and add them.
Step 1. Add the ones. Step 2. Add the tens. Step 3. Add the hundreds.

H T O H T O H T O

2 7 1 2 7 1 2 7 1
+ 3 2 5 + 3 2 5 + 3 2 5

6 9 6 5 9 6

Therefore, 271 + 325 = 596.
Addition with regrouping

regrouping ones
When we have more than 9 ones, we can regroup 10 ones into 1 ten.

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

Example 2. Add 324 and 256. H T O
Solution. Write the numbers in columns and 1
add them. 3 2 4

Step 1. Add the ones. + 2 5 6

4 + 6 = 10 ones
Regroup 10 ones as 1 ten 0 ones. 0

Write 0 in the ones place and carry over 1 to the tens column.
Step 2. Add the tens. Step 3. Add the hundreds.

H T O H T O

1 1
3 2 4 3 2 4

+ 2 5 6 + 2 5 6

8 0 5 8 0

1 + 2 + 5 = 8 tens 3 + 2 = 5 hundreds
Write 8 in the tens place. Write 5 in the hundreds place.
Therefore, 324 + 256 = 580.

40 Mathematics 3