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Team Selection Test

Turkey number theory

Problem

Find the largest positive integer which is divisible by all positive integers whose cube is not greater than .
Solution
The answer is .

Let us consider the positive integer so that . As satisfies the conditions, we will consider the case when . Note that each of , , and divides and hence divides . Since , divides and divides , we have that

divides . Therefore, and hence .

If or , then , but .

If or , then , but .

If , then , but .

If , then and . Therefore .
Final answer
420

Techniques

Greatest common divisors (gcd)Least common multiples (lcm)Floors and ceilings