Cool Maths Calculation Short Tricks/Cuts.

Cool Maths, isn’t it interesting to call Maths cool? Well, the answer is yes. Let’s see how:

Simplification has always been an integral part of aptitude question papers. The problems on Simplification test how good you are at calculation? The speed of solving the problems depends on your proficiency in certain maths topics like multiplication, addition, squares, cubes and square roots etc. If you know short tricks of calculations, you can solve the problems in relatively short time, and it will also increase your accuracy in the answers.

In Cool Maths Short Tricks, we will learn a few calculation short tricks by practicing them and solving the assignment.

Trick to multiply numbers by 50.

       Step 1: Divide the given number by 2.

       Step 2: If the given number is even, then add two zeros at the end of the result of the step 1.

       Step 3: If the given number is odd, remove the decimal point and add one zero.

1. 46 X 50
   1. 46 / 2 = 23
   2. Add two zeros at the end of 23

Ans. 2300

2. 124 X 50
   1. 124 / 2 = 62
   2. Add two zeros at the end of 62

Ans. 6200

3. 628 X 50
   1. 628 / 2 = 314
   2. Add two zeros at the end of 314

     Ans. 31400

• Now, we will see if the given number is odd:

1. 73 X 50 
   1. Divide the number by 2

                    73 / 2 = 36.5 (It will give you the result in decimal form)

2. Remove the decimal point and add only one zero.

Ans. 3650

2. 147 X 50
   1. 147 / 2 = 73.5
   2. Remove the decimal point and add one zero at the end of 735

Ans. 7350

3. 429 X 50
   1. 429 / 2 = 214.5
   2. Remove the decimal point and add one zero at the end of 2145

Ans. 21450

Key Point: When you divide the number by two, try to calculate it mentally. Don’t use pen and paper. You just need to half the given number and add zeros accordingly. 

Trick to multiply numbers by 25.

       Step 1: Divide the number by 4. We can do this by half the given number by 2 and then again 

                     half that number by 2.

       Step 2: If there is no decimal point in final result in step 1, add two zeros at the end of the

                     result.

        Step 3: If  a decimal point occurs, we will add the zeros accordingly.

1. 68 X 25

1. 68 / 2 = 34

34 / 2 = 17

1. There is no decimal point in 17, add two zeros at the end of 17.

Ans. 1700

2. 84 X 25

1. 84 / 2 = 42

42 / 2 = 21

2. There is no decimal point in 21. So, we will add two zeros at the end of 21.

Ans. 2100

3. 128 X 25

1. 128 / 2 = 64

64 / 2   = 32

2. There is no decimal point in 31. Add two zeros at the end of 31

Ans. 3200

• Now, we will see some examples when a decimal point occurs:

1. 54 x 25
2. 54 / 2 = 27 ( Here no decimal point in the first half)

27 / 2 = 13.5 

2. After dividing the number, we have a decimal point in 13.5, remove the decimal point and add one zero at the end of 135

Ans. 1350

2. 78 X 25
   1. 78 / 2 = 39

39 / 2 = 19.5

3. Remove the decimal point and add one zero at the end of 195

Ans. 1950

3. 31 X 25
   1.  31     / 2    = 15.5

15.5 / 2 = 7.75

4. Now, we have a decimal point in both the divisions. In this case, we will remove the decimal point in the final result of step a and will not add any zero.

Ans. 775

4. 87 X 25
   1. 87 / 2    = 43.5
5. / 2 = 21.75 

5. Remove the decimal point.

Ans. 2175

5. 153 X 25
   1. 153 / 2  = 76.5

76.5 / 2 = 38.25

b. Remove the decimal point.

Ans. 3825

6. 129 X 25
   1. 129 / 2  =  64.5

64.5 / 2 = 32.25 

b. Remove the decimal point.

Ans. 3225

Key Point: In the above examples, do you observe something?

Here in step a, after the number divide by 2, we have odd numbers before the decimal point like 15 in 3^rd and 43 in 4^th example , then if we divide that number again by 2 it always gives you 75 after the decimal point.

In the 5^th and 6^th examples, after the number divide by 2, we have even numbers before the decimal point like 76 in 5^rd and 64 in 6^th example , then if we divide that number again by 2 it always gives you 25 after the decimal point.

Trick to multiply numbers by 11.

We will see the multiplication of two-digit number by 11.

1. 52 X 11 

5      2

5 + 2   

      5          7              2

Ans. 572

2. 87 X 11

8       7

8 + 7   

              15

                          8  + 1                5            7

9              5          7

Ans. 957

If there is any carry in the addition of two numbers, add that carry to the left side of the number.

Now, we will see the multiplication of three- digit number by 11.

1. 136 X 11

1 3 6

     1+3     3+6

                                       1         4         9 6

Ans. 1496

2. 597 X 11

5 9 7

          5+9     9+7           

      14         16               

                                     14+1                          

        1   5                                                     

                                  5+1                                                 

                    6     5         6     7

Ans. 6567

Here, we will always add the carry to the left side of the number.

Trick to calculate the square of numbers ending by digit 5.

1. Calculate the Square of 45

1. As we all know that square of 5 is 25. So, place 25 at the right side of your answer.
2. Multiply the left number by its successive number.

45 = 4 X 5 | 25 

     = 2025

2. Calculate the Square of 85

     85 = 8×9 | 25

          = 7225

3. Calculate the Square of 115

115 = 11×12 | 25

(Here we can use the shortcut trick of multiply by 11)

       = 13225

Final Thoughts

Solving problems can become a lot simpler with Cool Maths Short Tricks which are easy to use. These tricks could be very useful for students appearing for competitive exams or trying to learn Vedic maths.

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