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Problem 694

AMC 10/12, early questions
Number theory Difficulty 3.9 Find the answer Macedonian Mathematical Competitions · North Macedonia

Which digit has to be put in the place of the star in the number 20082008* in order to be divisible with 66?

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

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Official solution

In order 20082008* to be divisible with 66 it has to be divisible with 22 and 33. In order to be divisible with 22 it has to end on 00, 22, 44, 66 or 88. From the numbers 2008020080, 2008220082, 2008420084, 2008620086 and 2008820088 only 2008220082 and 2008820088 are divisible with 33. So on the place of the * we can put 22 or 88.

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