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Problem 19 (2020 AMC 8)

AMC 8Normal

From module Arithmetic and Number Theory Basics

Problem

A number is called flippy if its digits alternate between two distinct digits. For example, 20202020 and 3737337373 are flippy, but 38833883 and 123123123123 are not. How many five-digit flippy numbers are divisible by 1515?

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