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If n is an integer between 10 and 100, is the tens digit of n even?
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23 Aug 2015, 09:23
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If n is an integer between 10 and 100, is the tens digit of n even? (1) The remainder when n is divided by 4 is equal to the remainder when n is divided by 5. (2) The only prime factor of n is 3.
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Re: If n is an integer between 10 and 100, is the tens digit of n even?
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23 Aug 2015, 10:26
shasadou wrote: If n is an integer between 10 and 100, is the tens digit of n even? (1) The remainder when n is divided by 4 is equal to the remainder when n is divided by 5. (2) The only prime factor of n is 3. If n is an integer between 10 and 100, is the tens digit of n even? (1) The remainder when n is divided by 4 is equal to the remainder when n is divided by 5. First of all, since the remainder is less than the divisor then the remainder must be 0, 1, 2, or 3. n = 4q + r; n = 5p + r; 4q + r = 5p + r; 4q = 5p > q/p = 5/4 > q must be a multiple of 5 and p must be a multiple of 4. Thus, n = 4q + r = 4(5k) + r = 20k + r = (a multiple of 20) + r > n could be 20, 21, 22, 23, 40, 41, 42, 43, 60, 61, 62, 63, 80, 81, 82, or 83. In any case the tens digit of n is even. Sufficient. (2) The only prime factor of n is 3 > n = 3^m. Since n is between 10 and 100, then it can be 3^3 = 27 or 3^4 = 81. In any case the tens digit of n is even. Sufficient. Answer: D. Hope it's clear.
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Re: If n is an integer between 10 and 100, is the tens digit of n even?
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08 Mar 2017, 04:55
ST 1: LCM is 20. hence the number can be 20, 21, 22, 23,40, 41,42,43, 60,61, 62, 63, 80, 81, 82, 83. All the cases, the tens digit is even. ANSWER
St 2: the possibilities are 03,09,27,81. All the cases, the tens digit is even.
Option D



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Re: If n is an integer between 10 and 100, is the tens digit of n even?
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16 Mar 2018, 02:46
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Re: If n is an integer between 10 and 100, is the tens digit of n even? &nbs
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