Assuming here the question means multiplication, we know that
.....9 * xy = n (9 will be the units digit when 243 is multiplied with 463)
(1)
Not enough, since x = 6 y = 1 will result in a unit digit of 4 (...9 x 6), and x = 4 y = 3 will result in a units digit of 8 (...9 x 12)
(2)
Not enough
x = 4 reduces the question further to ....6*y = n
Depending on y, n could take any units digit.
Combining (1) and (2), we know that x = 4, y = 3
Question reduces to ...9 x 12, so n will have a units digit of 8.
(C) should be the answer. OA please?
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Digits, power
Source: Beat The GMAT — Data Sufficiency |
Not sure about OA or whether I am wrong but IMO (C).
243*463 = units digit = 9.
so 9*xy=n
(1) x+y=7
there are so many combination's of x+y that can give you 7. and if we take each of those values and multiply it with 9, we get different answers.
Insufficient.
(2) x=4
so 9*y*4
then we have 6*y
Now y could be anything. therefore, this one is also insufficient.
Together:
4+y=7
x=4
y=3
9*4*3
8 is the units digit.
243*463 = units digit = 9.
so 9*xy=n
(1) x+y=7
there are so many combination's of x+y that can give you 7. and if we take each of those values and multiply it with 9, we get different answers.
Insufficient.
(2) x=4
so 9*y*4
then we have 6*y
Now y could be anything. therefore, this one is also insufficient.
Together:
4+y=7
x=4
y=3
9*4*3
8 is the units digit.
"Do not confuse motion and progress. A rocking horse keeps moving but does not make any progress."
- Alfred A. Montapert, Philosopher.
- Alfred A. Montapert, Philosopher.
No wonder!uwhusky wrote:The question is copied incorrectly.
https://www.beatthegmat.com/exponent-pro ... 24675.html
Thanks!
"Do not confuse motion and progress. A rocking horse keeps moving but does not make any progress."
- Alfred A. Montapert, Philosopher.
- Alfred A. Montapert, Philosopher.
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beatthegmatinsept
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That explains.. BTW, I got C too for the 'modified' question posted above.Gurpinder wrote:No wonder!uwhusky wrote:The question is copied incorrectly.
https://www.beatthegmat.com/exponent-pro ... 24675.html
Thanks!
Being defeated is often only a temporary condition. Giving up is what makes it permanent.
You can simply pretend they have the same base, since we are only concerned with the unit digit.
So even though it's 243^x * 463^y, you can simplify it down to 3^x * 3^y. We know that when two exponents have the same base multiplying, we simply add them together: 3^(x+y).
Answer is A.
Hope I am clear on this one.
So even though it's 243^x * 463^y, you can simplify it down to 3^x * 3^y. We know that when two exponents have the same base multiplying, we simply add them together: 3^(x+y).
Answer is A.
Hope I am clear on this one.
Yes you are,uwhusky wrote:You can simply pretend they have the same base, since we are only concerned with the unit digit.
So even though it's 243^x * 463^y, you can simplify it down to 3^x * 3^y. We know that when two exponents have the same base multiplying, we simply add them together: 3^(x+y).
Answer is A.
Hope I am clear on this one.
I was about the write the same thing.
Since we are ONLY dealing with units digits we simply need to be worried about the units digit.
so the question becomes 3^x * 3^y as you pointed out. And modifying this > 3^7
So stmt 1 is sufficient.
"Do not confuse motion and progress. A rocking horse keeps moving but does not make any progress."
- Alfred A. Montapert, Philosopher.
- Alfred A. Montapert, Philosopher.
