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## Wednesday, August 9, 2023

### How to Add Numbers Quickly using Mental Math Techniques

Here are a few examples demonstrating how to add numbers quickly using mental math techniques:

• Start with the units (ones) digit: 7 + 8 = 15. Write down 5 and mentally carry over 1.
• Move to the tens digit: 4 + 6 + 1 (carried over) = 11.

The sum is 115.

• Move to the tens digit: 5 + 8 = 13. Write down 3 and mentally carry over 1.
• Move to the hundreds digit: 3 + 4 + 1 (carried over) = 8.

The sum is 838.

• Add the thousands: 2,000 + 1,000 = 3,000.
• Add the hundreds: 300 + 700 = 1,000.
• Add the tens and ones: 40 + 80 = 120.

The sum is 3,000 + 1,000 + 120 = 4,120.

Example 4: Using Complementary Numbers Add: 87 + 46

• Find the difference between the larger number and 10 (87 - 10 = 77).
• Add the complement of the smaller number (46 + 3 = 49).
• Add the results: 77 + 49 = 126.

This technique is particularly useful when one of the numbers is close to a multiple of 10.