Calculate 24 * 99

Solution

1. Decrement one from the number. So here 24-1 = 23

2. Decrement each digit of the number obtained from 9. Here we got 23. Now 9-2 = 7 and 9-3=6. So we have 76

3. Just write these numbers together. That is we have 23 and 76. Hence answer is 2376

calculate 2358 * 9999

Solution

1. Decrement one from the number. So here 2358-1 = 2357

2. Decrement each digit of the number obtained from 9. Here we got 2357. Now 9-2 = 7 , 9-3=6 , 9-5=4 and 9-7=2. So we have 7642

3. Just write these numbers together. That is we have 2357 and 7642. Hence answer is 23577642

calculate 758 * 99999

Solution

1. Since the number of digits in 99999 is 5, we need to write 758 as 00758 in order to treat it as a 5 digit number

1. Decrement one from the number. So here 00758-1 = 00757

2. Decrement each digit of the number obtained from 9. Here we got 00757. Now 9-0=9, 9-0=9, 9-7=2, 9-5=4, 9-7=2. So we have 99242

3. Just write these numbers together. That is we have 00757 and 99242. Hence answer is 0075799242 or 75799242

here 12158*999 .It has 3 9's and other number has 5 digit

So divide the other number in to two group from right .Where right most group contain as much digit as number of 9s

that is 12158 to 2 group 12 and 158(because 3 9's)

then add 1 to the left group 12+1=13

now subtract this number from original number : 12158 - 13 = 12145

now take right most group 158 subtract it form 999+1 : 1000 - 158 = 842

So the result is combine this group 12145842

__example 2__

45612*999

45 and 612

45+1=46

45612 - 46 = 45566 => 1

1000 - 612 = 388 => 2

combine 1 and 2 => 45566388

__example 3__

4214*999

4 and 214

4214 - 5 = 4209

1000 - 214 = 786

so answer is 4209786

One method for such cases is 12158 * 999 = 12158(1000-1) = 12158000 - 12158 = 12145842

1) 8413-1=8412

2)9999+1=10000-8413=1587

Ans: 84121587

786*99

First take last 2 digit: 86

100 - 86 = 14

Write down at right : 14

Then add 1 to first digit :1+7=8

Then 786 - 8 = 778

Right answer is 77814

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