2013 AMC 10B Problem 25AMC 10 Step by Step
Name: Date: September 13, 2026
Bases & Digits · difficulty 5 of 5 · about 12 min · position P21-25
Bernardo chooses a three-digit positive integer and writes both its base-5 and base-6 representations on a blackboard. Later LeRoy sees the two numbers Bernardo has written. Treating the two numbers as base-10 integers, he adds them to obtain an integer . For example, if , Bernardo writes the numbers and , and LeRoy obtains the sum . For how many choices of are the two rightmost digits of , in order, the same as those of ?
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