Congruence and Modular Arithmetic

FLT actually follows from the more general

## Fermat’s Little Theorem (F$l$T)

For all prime numbers $p$ and integers $a$ not divisible by $p$, we have $a_{p−1}≡1(modp)$

#### Corollary for Fermat’s Little Theorem

$a_{p}≡a(modp)$

“Fermat’s Little Theorem gives $a_{(p−1)}≡a(modp)$ if gcd(a, p)=1, where p is a prime. Therefore, we can calculate the modular inverse of a as a^(p-2), by fast exponentiation also.”