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Showing posts with label Additions Shortcuts. Show all posts
Showing posts with label Additions Shortcuts. Show all posts

Saturday, 21 August 2010

Additions Shortcuts


 Additions Shortcuts

Addition of numbers close to multiples of ten (e.g. 19, 29, 38, 59 etc.)



This technique is useful for Mental calculations


116 + 39 (Here we can write this 39 as 40-1)
= 116 + (40 - 1)
= 116 + 40 - 1
= 156 - 1 (Instead of adding 39 to 116, we just add 40 to 116 (because we can do this without using pen and paper) and later we subtract one from it)
= 155
Try this.. This is very useful tip while doing calculations.


Now lets try another example. 
116 + 97
= 116 + (100 - 3)
= 116 + 100 - 3  (Here, instead of adding 97 to 116, we are just adding a 100 to 116 and then subtracting 3 from it :)
= 216 - 3
= 213


Addition of decimals

12.5 + 6.25
= (12 + 0.5) + (6 + 0.25) 
= 12 + 6 + 0.5 + 0.25 (Here we just added the rounded numbers first and later we added the decimal numbers :)
= 18 + 0.5 + 0.25
= 18.75

00:08 - By Unknown 0

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