2 ms·
Alternative proof: From Fermat's little theorem: n^5 ≡ n (mod 5). Therefore (n^5 - n) is divisibe by 5. (n^5 - n) is always even, so it's also divisble by 10
by jwilk 9y ago
Alternative proof:
From Fermat's little theorem: n^5 ≡ n (mod 5).
Therefore (n^5 - n) is divisibe by 5.
(n^5 - n) is always even, so it's also divisble by 10.