2012 AIME II Problems/Problem 12

Revision as of 16:11, 31 March 2012 by Williamhu888 (talk | contribs) (Created page with "== Problem 12 == For a positive integer <math>p</math>, define the positive integer <math>n</math> to be <math>p</math>''-safe'' if <math>n</math> differs in absolute value by mo...")
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Problem 12

For a positive integer $p$, define the positive integer $n$ to be $p$-safe if $n$ differs in absolute value by more than $2$ from all multiples of $p$. For example, the set of $10$-safe numbers is $\{ 3, 4, 5, 6, 7, 13, 14, 15, 16, 17, 23, \ldots\}$. Find the number of positive integers less than or equal to $10,000$ which are simultaneously $7$-safe, $11$-safe, and $13$-safe.