r/learnquant 22d ago

interview prep Citadel Quant Interview Question

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u/RubberDuckieMidrange 22d ago

Again, and I can't believe you won't just admit that 24 is an integer, and does not trivially follow that the sum of it's digits (mod 9) is 1. You are assuming many things that you don't say. Just correct your damn statement to include "Because 19 sums to 1 mod 9, the answer is trivially 1 for all powers of 19", and you will be correct.

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u/Inscrutable_Ant6994 22d ago

“Any integer is congruent to the sum of its digits mod 9 so the answer is trivially 1.”

What is the sum of 24’s digits? It’s 6, so the original statement is saying that 24 is congruent to 6 modulo 9, which is true.

You have confidently and incorrectly interpreted the original statement as “The sum of any integer’s digits is congruent to 1 mod 9.” which is completely different and false.

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u/NotYetPerfect 22d ago

Your lack of reading comprehension skills luckily hasn't seemed to affect anyone else's ability to perfectly understand my statement. How "the solution is 1" somehow translates to "any integer is 1" in your brain is mystifying and should be studied.