What is $(65!)^2$ congruent to mod $131$?
7932
$(p\!-\!1\!-\!h)!\,h! \equiv (-1)^{h+1}\!\!\pmod{\! p}\,$ [Wilson Reflection Formula]
9039
What is the best way to solve modular arithmetic equations such as $9x \equiv 33 \pmod{43}$?
43683
Finding Inverse of 2 (mod m)
9787
Primitive roots modulo primes congruent to n!
30045
Solving linear congruences by hand: modular fractions and inverses
146053
Proving identities (mod $pq$) using Fermat's little theorem?
152039
Prove that $a^{2^n}=1 \mod 2^{n+2}$
105225
Number Theory: Complete set of residues modulo $n$
144067
calculating $a^b \!\mod c$
58803
${n \choose k} \bmod m$ using Chinese remainder theorem?
25299
What is the remainder when $2^{1990}$ is divided by $1990$?
38727
Modular Exponentiation and Primes
60305
Proving the congruence $p^{q-1}+q^{p-1} \equiv 1 \pmod{pq}$
22029
Solving modular arithmetic questions
29204
$a\equiv\bar a\!\pmod{\!kn}\Rightarrow a\equiv\bar a\!\pmod{\! n};\ $ $(a\bmod kn)\bmod n=a\bmod n.\ $ Congruences persist mod factors of the modulus
66861
Show that $11^{10} \equiv 1 (\mod 100)$
10105
Proving $\, a^b = (a\bmod n)^b\, \pmod{\!n}\ $ [Congruence Power Rule]