Shortcuts to Perform Mathematical Operations

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Friends, we have already discussed the following methods in our various posts which we have updated earlier. In this post we are just summarizing all those simple time saving techniques with examples so that it will be easier for you to have a quick review.

Addition Shortcuts : 

Add 37 and 38

We can solve this problem in many ways.

• 37+30+8 = 75
• 37+3+35 = 75
• 37 + 40 - 2 = 75

Subtraction Shortcuts :

Subtract 25 from 67

Since 25 = 20 + 5 ,

67-25 = 67 - 20 - 5 = 42

Multiplication Shortcuts :

Multiply 12 and 50

12 x 50 = 12 x 5 x 10

= 60x10 = 600

(You can actually multiply by 5 and then add a zero to it)

Note : We all know that, to multiply a number by 10, 100 or 1000, we add zeroes at the end of the given number.

28x10 = 280

325x100 = 32500

4623 x 1000 = 4623000

So if you want to multiply 5 with any number, then just add a zero to it and divide it with 2.

28 x 5 = 280/2 = 140

Multiply 569 x 99

We can use the same method explained above to solve this problem

as 99 = 100-1

569 x 99 = 569 x (100-1)

= 569 x 100 - 569 x 1

= 56900 - 569 = 56331

To multiply by 25, as 25 = (100/4), it is enough if we multiply the number by 100 and then divide the same by 4.

Multiply 64 and 25

We will consider 25 as 100/4 to solve this problem.

64 x 25 = 64x(100/4)

= 16x100 = 1600

Multiply 64 and 50

To multiply by 50, as 50 = 100/2,

it is enough if we multiply the number with 100 and then divide by 2.

64 x 50 = 64x (100/2) = (64/2) x 100 = 32x100 = 3200

Therefore, 64 x 50 = 3200

Multiply 105 x 51

We can take 51 as 50+1

so, 105 x 51

= 105 x (50+1)

= 105 x 50 + 105 x 1

=  ((105 x 100)/2) + 105 = (10500/2_ + 105 = 5250 + 1058 = 5355

Therefore, 105 x 51 = 5355

Multiply 64 x 125

To multiply a number by 125, as 125 = 1000/8, we can multiply the number by 1000 and then divide by 8.

64 x 125 = 64 x 1000/8

 = 64/8 x 1000 = 8x1000 = 8000

Therefore, 64x125 = 8000

Multiply 648 x 127

We can take 127 as 125+2

648x127 = 648x(125+2)

= 648x125 + 648x2

= 648 x (1000/8) + 648x2

 = 8100 x 1296

= 82296

now let us move on to the problems of divisions.

Division Shortcuts :

Note : While performing division, sometimes, the divisor can be converted into a fraction of 10, 100 or 1000. But you must remember to change the numerator accordingly in order to keep the value unchanged.

Divide 1500 % 500

1500/500 = (1500x2) / (500x2)

= 3000/1000 = 3

Simplify 350%50

350/50 = (350x2) / (50x2)  = 700/100 = 7

Divide 420 % 20

= 420/20 = (420x5)/(20/5)

= 2100/100 = 21

That's all for now friends. You can check detailed shortcut techniques of math from here. Happy Reading.

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