Now, we are going to show you how to do Additions Mentally. Have a look at
Example-1
| 425 + 336 + 927+ 811 + 222 = ? |
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| while adding three-digit numbers, first add-two-digits at a time (Units and Tens Place). 25 + 36 + 27 + 11 + 22 = 121 To add 25 and 36, mentally treat 25 as 20 + 5 and 36 as 30 +6 So, 20 + 30 = (20 + 30) + 5 + 6 = 61 Similarly, 61 + 27 = (60 + 20 + 7 + 1 = 88 88 + 11 = (80 +10) + 8 + 1 = 99 99 + 22 = (90 + 20) + 9 +2 = 121 The last two digits (the units place and the tens place) of the addition are 21, while the digit 1 is to be carried forward). Now Add, 1 (Carried) + 4 + 3 + 9 + 8 + 2 = 27 So, the answer of the above addition is 2721 (initially, it may look confusing. Just practice this method and you can find how efficient this method is : The same logic can be extended to 4 digit additions too... have a look |
Example-2
| 3425 +4336 + 2927 + 811 + 4222 = ? |
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| Now, we are going to show you how to do Additions Mentally. Have a look at 3425 +4336 + 2927 + 811 + 4222 Part-1 25 + 36 + 27 + 11 + 22+ ? while adding three-digit numbers, first add-two-digits at a time (Units and Tens Place). 25 + 36 + 27 + 11 + 22 = 121 To add 25 and 36, mentally treat 25 as 20 + 5 and 36 as 30 +6 So, 20 + 30 = (20 + 30) + 5 + 6 = 61 Similarly, 61 + 27 = (60 + 20 + 7 + 1 = 88 88 + 11 = (80 +10) + 8 + 1 = 99 99 + 22 = (90 + 20) + 9 +2 = 121 The last two digits (the units place and the tens place) of the addition are 21, while the digit 1 is to be carried forward). Part-2 Now Add, 1 (Carried) + 34 + 43 + 29 + 8 + 42 = 277 30 + 40 +20 + 40 + 1 (carry) +4 + 3 + 9 + 8 + 2 =157 So, the answer of the above addition is 15721 . The same logic can be extended to 5 , 6 , 7 and so on digit additions too. |