Shortcuts to Perform Mathematical Operations
Addition Shortcuts :
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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