Generalizing the Chinese remainder theorem with fibred products
62711
Canonical map $R/(I\cap J)\rightarrow R/I\times _{R/(I+J)} R/J$ is an isomorphism
28109
Conjectural closed-form representations of sums, products or integrals
9118
Polynomial division: an obvious trick? [reducing mod $\textit{simpler}$ multiples]
41726
Musical and combinatorial proof
125115
Simplifying Large Bases with large Exponents
107349
Working with elementary type proofs of divisor functions
43155
Cyclotomic Polynomials and GCD
129476
The trace map in a finite field.
52774
Computing an infinite sum using the Residue theorem
30630
Proving ${n \choose p} \equiv \Bigl[\frac{n}{p}\Bigr] \ (\text{mod} \ p)$
129827
Product of invertibles in $\Bbb Z_n$ [Wilson's Theorem generalization]
114164
Square-free Integers Factorization
118560
Ordered N-Tuples as Cartesian Products of Indexed Families
93820
Fermat's little theorem applied for $n$'th root existence $\!\bmod p$
30045
Solving linear congruences by hand: modular fractions and inverses
360
Modular exponentiation by hand ($a^b\bmod c$)
132118
Computing the $n^{\textrm{th}}$ permutation of bits.