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Step 4. Add the thousands and regroup. Step 5. Add the ten thousands.

TTh Th H T O TTh Th H T O
1 1 1 1 1 1 1 1
3 6 9 7 6 3 6 9 7 6

+ 5 7 8 9 8 + 5 7 8 9 8
4 8 7 4 9 4 8 7 4

Therefore, 36976 + 57898 = 94874.

Example 3. Add the following numbers:

a. 4364 + 1792 + 73645 b. 20436 + 18369 + 42178

Solution. a. TTh Th H T O b. TTh Th H T O
1 2 1 1 1 2
4 3 6 4 2 0 4 3 6
1 7 9 2 1 8 3 6 9

+ 7 3 6 4 5 + 4 2 1 7 8

7 9 8 0 1 8 0 9 8 3

Checking Addition
To check a sum, we add the numbers from the bottom-up. This is called adding up.

Example 4. Find the sum of the following numbers and check the sum.
a. 2736 + 4187 = ? b. 56143 + 27682 = ?

Solution. a. Th H T O b. TTh Th H T O
2 7 3 6 Adding 5 6 1 4 3 Adding

+ 4 1 8 7 down + 2 7 6 8 2 down

6 9 2 3 Sum 8 3 8 2 5 Sum

Th H T O TTh Th H T O

6 9 2 3 Sum 8 3 8 2 5 Sum

+ 2 7 3 6 Adding + 5 6 1 4 3 Adding
4 1 8 7 up 2 7 6 8 2 up

We get the same sum in both the We get the same sum in both the

cases. So, the sum is correct. cases. So, the sum is correct.

28 Mathematics 4