Divisibilityhard
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A student proposes the following divisibility test for a prime : 'Split the decimal representation of the number from right to left into blocks of 3 digits. Find the alternating sum of these blocks. If this alternating sum is divisible by , then the original number is divisible by .' For which of the following sets of primes is this test mathematically valid?
A student proposes the following divisibility test for a prime : 'Split the decimal representation of the number from right to left into blocks of 3 digits. Find the alternating sum of these blocks. If this alternating sum is divisible by , then the original number is divisible by .' For which of the following sets of primes is this test mathematically valid?