Let S be a set of positive integers such that every element n of S satisfies the conditions
A. 1000 <= n <= 1200
B. every digit in n is odd
Then how many elements of S are divisible by 3?
The no. has all the digits as odd no. and is divisible by 3. So the possibilities are
1113
1119
1131
1137
1155
1173
1179
1191
1197
Hence 9 possibilities .
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