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Hi more questions again... i am having a hard time figuring out these questions...

1)a)how many 6-digit palindromic numbers are there???

(i can do this the slow way, but i am looking for shortcuts)

b) how many odd 7-difit palindromic numbers are there in which every digit appears at most twice?

( again, i am looking for a fast way)

2)show that if 14 distinct intergers are chosen form the sequence 100, 101,102, 103......,123,124, there must be two of them whose difference is 4

(i have worked this out by writing out 14 numbers and having all the possibilities(it took a long time) and i am looking for a shortcut)

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# More questions?

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