Let , and be positive integers such that is divisible by , is divisible by and is divisible by . Find the least possible value of .
, 2010
Solution
Since is divisible by and is divisible by , must be divisible by , hence is divisible by . Therefore is divisible by and , hence is divisible by and . Similarly is divisible by and , and is divisible by and . Consequently is divisible by . On the other hand, , and satisfy the conditions and .
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