Recommended -Calculate Mentally (Don't use pen, paper and pencil)
It is very useful tip.Just take it in your habit.
Method-1
Method-2-Take a look
It is very useful tip.Just take it in your habit.
Method-1
Example-1
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Example-2
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|---|---|
216 + 87 (Take last 2 digits at a time from both numbers .Here we can write 16 as 20-4 and 87 as 90-3)
= (20-4) + (90 - 3) (and add carry with 2)
= (20+90)-(4 +3)
= (110)-7 (carry is 1 in 110.So add 1 with 2 )
= 03 (put 3=1+2 at third place)
=303
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296 + 510 (Take last 2 digits at a time from both numbers .here we can write 96 as 100-4 and 10)
= 96+10 (and add carry with 5 and 2)
= 106 (carry is 1 in 110.So add 1 with 2 and 5 in next step )
= 06 (put 2+5+1 (carry) at third place)
=806
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Method-2-Take a look
| Example-3 | Example-4 |
|---|---|
116 + 29 ( we can write this 29 as 30-1)
= 116 + (30 - 1)
= 116 + 30 - 1
= 146 - 1 (Instead of adding 29 to 116, we just add 30 to 116 we can do this without using pen and paper and later we subtract one from it)
= 145
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341 + 71 (here we can write this 71 as 71+1)
= 341 + (70 +1)
= 341 + 70+1 (Here, instead of adding 70 to 341, we are just adding a 70 to 341 and then add 1 )
= 411+1
= 412
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Example-5
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Example-6
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116 + 38
= 116 + (40 - 2)
= 116 + 40 - 2 ---> add 40 then subtract 2
= 156 - 2
= 154
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116 + 98
= 116 + (100 - 2)
= 116 + 100 - 2 ---> add 100 then subtract 2
= 216 - 2
= 214
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Practice Time:
Recommended-Do it in 3 min
1- 215 + 28=
2- 197 + 88=
3- 587 + 91=
4- 856 + 987=
5- 566 + 76=
6- 456 + 56=
7- 56 + 786=
9- 444 + 555=
10- 234 + 67=