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How many 8 digit positive integers in the form ABCD2873 are divisible by 221 ?
Автор: My One Fiftieth Of A Dollar
Загружено: 2025-11-20
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Rudimentary combinatorics problem not olympiad level.
How Many 8 Digit Integers Ending In 2873 Are Divisible By 221. Prime factorizations of both constants important.
Divisibility test for 13 is to multiply last digit by 4 and add it to what remains. If resulting sum is divisible by 13 then so is the original number.
For example considering 221 gives 22 + 4*1 = 26 which is manifestly divisible by 13. Mathematician math tutor Harsh Kumar produced a proof of this December 2016 at math stack exchange. It is unnecessary to state this divisibility test is recursive(In fact it is almost wrong to state something so obvious)
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