## December 20, 2011

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

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

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16. Its useful....thank u so much

17. nice trick to mental calculation

18. nice trick i want more like this

19. nice work keep it up..thanks

20. please provide more techniques....it is very nice but getting problems in exams is some difficult.. thanq

1. Sure neeru. we will :)

All the best :)

22. V.useful tips

23. Useful tips

24. i didn't find it useful b'coz these are cheeze tricks , but still writer did well according to him, difficulty level of question is much higher.

1. not much higher,if one considers individual & total cutoffs both then it becomes much much much higher

25. nice tricks

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32. Came across this site today. Learnt a lot within a short time. Really understandable in a short span of time. Thanks a lot. Cheers! :)

33. i too hav a shortcut trick for quick addition i.e Q)3245+4356+2453+7896=17950.
now we start from right hand side 6+3+6+5=20 .we will write 0. again add 2(carry forwd)+9+5+5+4=25 now we wll write 5. again add 2+8+4+3+2=19, write 9. add 1+7+2+4+3=17 this tym we will write 17 so the ans is 17950. this can be done in mind only after thoroughly practicing.

34. Very helpful .. Thank a lot

35. Realy nice one..

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41. thanks , these tricks are very helpful...................

42. really helpful, thanx a ton.

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