Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 15)
15.
72519 x 9999 = ?
Answer: Option
Explanation:
| 72519 x 9999 | = 72519 x (10000 - 1) |
| = 72519 x 10000 - 72519 x 1 | |
| = 725190000 - 72519 | |
| = 725117481. |
Discussion:
15 comments Page 1 of 2.
Anurag said:
3 years ago
@All.
The best short trick to multiply any digit with 99,999,999,99999999,..
Example;
33 * 99 = 33 -1 || 9-3 || 10-3 => 3267.
237 * 999 = 237-1 || 9-2 || 9-3 || 10 - 7 (10 - last digit) => 236763.
The best short trick to multiply any digit with 99,999,999,99999999,..
Example;
33 * 99 = 33 -1 || 9-3 || 10-3 => 3267.
237 * 999 = 237-1 || 9-2 || 9-3 || 10 - 7 (10 - last digit) => 236763.
(2)
Manoj said:
4 years ago
From where do we get 5x?
(2)
Aashu said:
4 years ago
7 + 2 + 5 + 1 + 9 = 24 again 2 + 4=6
9 + 9 + 9 + 9 = 36 again 3 + 6 =9
Given =72519 * 9999 = 9 * 6 = 54 sum of 5 + 4= 9
Now find the sum of the digits in the given option
A)7 + 2 + 5 + 1 + 1 + 7 + 4 + 8 + 1 = 9,
Similarly for
B)4
C)5
D)8
So, option A is the correct answer. Hope my answer is useful.
9 + 9 + 9 + 9 = 36 again 3 + 6 =9
Given =72519 * 9999 = 9 * 6 = 54 sum of 5 + 4= 9
Now find the sum of the digits in the given option
A)7 + 2 + 5 + 1 + 1 + 7 + 4 + 8 + 1 = 9,
Similarly for
B)4
C)5
D)8
So, option A is the correct answer. Hope my answer is useful.
(13)
Mustafa said:
6 years ago
This trick always works if m * n when the numbers in m > n and n = any number of 9's sequence.
1) Count number of 9's in n.
2) Add those many 0's in the m number.
3) Subtract the original number.
eg> 72519 * 9999.
m=5 , n = 4 thus m>n.
721590000-72519= 725117481.
1) Count number of 9's in n.
2) Add those many 0's in the m number.
3) Subtract the original number.
eg> 72519 * 9999.
m=5 , n = 4 thus m>n.
721590000-72519= 725117481.
(1)
Mustafa said:
6 years ago
It works if m * n when the numbers in m > n and n = any number of 9's sequence.
1) count number of 9's in n.
2) add those many 0's in the m number.
3) subtract the original number.
eg> 72519 * 9999.
m=5 , n = 4 thus m>n.
721590000-72519= 725117481.
1) count number of 9's in n.
2) add those many 0's in the m number.
3) subtract the original number.
eg> 72519 * 9999.
m=5 , n = 4 thus m>n.
721590000-72519= 725117481.
(1)
Smit said:
7 years ago
If we multiply all then option C is correct.
Vamsi aripaka said:
7 years ago
Thank for explaining the solution.
(1)
Roshan said:
9 years ago
I think it's 72446481.
Is it correct?
Is it correct?
(3)
Krishnamurthy said:
9 years ago
The easiest method can be:
72519 x 9999.
If the multiplier is series of 9 (i. e. 9, 99, 999. ) then,
Add every digit in the given answer (i.e. 7 + 2 + 5 + 1 + 1 + 7 + 4 + 8 + 1 = 36, add the answer again, i.e. 3 + 6 = 9).
And if the final answer is 9 then that number itself answers.
72519 x 9999.
If the multiplier is series of 9 (i. e. 9, 99, 999. ) then,
Add every digit in the given answer (i.e. 7 + 2 + 5 + 1 + 1 + 7 + 4 + 8 + 1 = 36, add the answer again, i.e. 3 + 6 = 9).
And if the final answer is 9 then that number itself answers.
Sree said:
9 years ago
It is very simple method 72519 * 9999.
72519 * 9000 = 652671000,
72519 * 900 = 65267100,
72519 * 90 = 6526710,
72519 * 9 = 652671.
Then 652671000 + 65267100 + 6526710 + 652671 = 725117481.
72519 * 9000 = 652671000,
72519 * 900 = 65267100,
72519 * 90 = 6526710,
72519 * 9 = 652671.
Then 652671000 + 65267100 + 6526710 + 652671 = 725117481.
(1)
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