Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 65)
65.
If the number 42573 * is exactly divisible by 72, then the minimum value of * is:
Answer: Option
Explanation:
72 = 9 x8, where 9 and 8 are co-prime.
The minimum value of x for which 73x for which 73x is divisible by 8 is, x = 6.
Sum of digits in 425736 = (4 + 2 + 5 + 7 + 3 + 6) = 27, which is divisible by 9.
Required value of * is 6.
Discussion:
17 comments Page 2 of 2.
Koti Ch said:
10 years ago
May I know about co prime numbers?
Ritvik said:
1 decade ago
If you count the digits except * it comes to be 21. Now place one by one options and add it up and check the divisibility by 3.
Only option C and D satisfies but option D doesn't satisfy divisibility rule of 9. Clearly answer is 6 i.e. option C.
Only option C and D satisfies but option D doesn't satisfy divisibility rule of 9. Clearly answer is 6 i.e. option C.
RamPavan said:
1 decade ago
Good problem and Easy for solving is also available.
Ashith said:
1 decade ago
72 = 2^3+3^2.
Apply divisibility rule of 2 and 3 on 42573x.
4+2+5+7+3+x = 21+x should be divisible by 3 if and only if x is 6.
Apply divisibility rule of 2 and 3 on 42573x.
4+2+5+7+3+x = 21+x should be divisible by 3 if and only if x is 6.
Rajasekar said:
1 decade ago
There is a simple way:-
72 is a multiple of 3, since 42573x is divisible by 72 (given).
Hence: 4+2+5+7+3+x = 21+x (which must be a divisible by 3).
From the given options 6 is the only option which fits in place of x to satisfy the above criteria.
Hope you understood.
72 is a multiple of 3, since 42573x is divisible by 72 (given).
Hence: 4+2+5+7+3+x = 21+x (which must be a divisible by 3).
From the given options 6 is the only option which fits in place of x to satisfy the above criteria.
Hope you understood.
Faizal said:
1 decade ago
The divisibility rule for 8 is :
You have to take the last 3 digit no and divide it by 8 if it is divisible by then the no will be divisible by 8.
Hope you understood.
You have to take the last 3 digit no and divide it by 8 if it is divisible by then the no will be divisible by 8.
Hope you understood.
Soniya said:
1 decade ago
Sir, I am unable to solve this, because when x=6 then we get 27 which is divided by 9 not by 8, then how answer is x=6.
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