Sometimes it is possible to find the modular inverse of a by inspection, especially if the modulus is small. For example, in mod 10, the inverse of 3 is 7 since 3*7=21 is congruent to 1 mod 10.
Sometimes it is possible to find the modular inverse of a by inspection, especially if the modulus is small. For example, in mod 10, the inverse of 3 is 7 since 3*7=21 is congruent to 1 mod 10.