Number Theory Modular arithmetic Used to define a finite field a=b mod n means that if a and b are divided by n they produce the same remainder a b mod n can result in o even if a and b are not o a/b mod n is calculated by a b-l mod n, where b-l is the inverse ofb. b*b-l=l mod nNumber Theory • Modular arithmetic – Used to define a finite field – a = b mod n means that if a and b are divided by n they produce the same remainder – a*b mod n can result in 0 even if a and b are not 0 – a/b mod n is calculated by a*b-1 mod n, where b -1 is the inverse of b, b*b-1 = 1 mod n