kvcpk wrote:M1 = 6, M2 = 96, M3 = 996,... Mk = 10^k -4
qn is is 10^k -4 divisible by an even number q??
1) q<45
10^k-4 is an even number.
hence q=2 will divide Mk
q=8 will not divide. Because M1 = 6 which is not divisible by 8.
INSUFF
2) Atleast 2 terms in the sequence are div by q.
q=2 will divide atleast 2 terms and also divides all terms.
q=12 will divide 96 and 996.. but it willnot divide M1 = 6
hence INSUFF
Combining:
We still have q=2 that satisfies both the conditions and also dividea all terms.
q =12 which also satisfies both the conditions but does not divide all terms.
Hence INSUFF
pick E.
Whats OA?
I agree the answer is E. I'd just like to point out a way to find the two qs for (2): all the numbers are even so q=2 is a possibility. for the seocnd one, note that 10^k is divisible by 4 (any integer power of 10, except for 10 itself, will be divisible by 4), so (10^k-4) will also be a multiple of 4: multiple of 4 - multiple of 4 = multiple of 4.
Thus, all of the terms except for M1 will be divisible by 4.
Since q could equal 2 or 4, with an answer if "yes" for the first and "no" for the second, and stat. (1) does not rule these two examples out, the answer is E.
