Possible remainders of a square
Number Theory
Level
5
Let \[N= 3 \times 5 \times 7 \times 11 \times 13.\] There are \(X\) possibilities for the units digit of a perfect square when it is represented in base \(N.\) Compute the last three digits of \(X\) (in base 10).
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Details and Assumptions:
- We are talking about \(3, 5, 7, 11, 13\) in their decimal representations.
- You might want to use the fact that \(3, 5, 7, 11, 13\) are all primes.
by
Sreejato Bhattacharya