Tip - 1
Addition Tricks - Calculation by Simplifying Numbers Principle of Equivalency
Example 1:
24 + 39
= (25 + 1) + (40 -1)
= 25 + 40
= 65
Note: Adding and subtracting '1' simplified the Addition but did not change The answer.
Example 2:
198 + 202
= (200 - 2) + (200 + 2)
= 200 + 200
= 400
Example 3:
414 + 596
= (410 + 4) = (600 -4)
= 410 + 600
= 1010
Principle of Equivalency : simplifying numbers by adding /subtracting / multiplying /dividing
Example 4:
64 × 25
= ([latex]\frac{64}{4}[/latex]) × (25 × 4)
= 16 × 100
= 1600
Here the terms are divided and multiplied by '4' to simplify calculation.
Solve:
1. 79 + 86
= (80 - 1) + (85 + 1)
= 80 + 85
= 165
2. 989 + 951
= (990 - 1) + (950 - 1)
= 990 + 950
= 1940
3. 1549 + 1701
= (1550 - 1) + (1700 + 1)
= 1550 + 1700
= 3250
Tip - 2
Addition Tricks - Addition of Similar Digit Numbers:
Commonly asked question in Competitive exams 7 + 77 + 777 = ? Answer: 7 * 123 = 861
The result of this particular problem 8 + 88 + 888 = 984
How can we quickly add these numbers? What is the shortcut/trick?
1. 8 is the common number in this sum so we take 8 and replace it with 1 so the sum now becomes 1 + 11 + 111.
2. Now count the number of digits in each number i.e. 1 = 1 digit, 11 = 2 digits, 111 = 3 digits and so on.
3. Write down all the digits together, in this case, it would be 123.
4. Now take the original common number 8 and multiply it by 123 = 984.
Example 1:
9 + 99 = 9(12) = 108
9 + 99 + 999 = 9(123) = 1107
9 + 99 + 999 + 9999 = 9(1234) = 11106