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:
16 comments Page 2 of 2.
Mustafa said:
7 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)
Mustafa said:
7 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)
Aashu said:
5 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.
(17)
Manoj said:
4 years ago
From where do we get 5x?
(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)
Abid said:
6 days ago
It is much easier if we find the sum of the digits. Only opt A's Digits' sum is divisible by 9.
So, that's the answer.
So, that's the answer.
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