Last time: Clock Arithmetic | Next time: 3.1: beyond numbers |
Today:
digit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
digit*3 mod 10 |
Computers can't quickly and efficiently factor humongous numbers.
Fermat's little theorem:
If p is a prime number and n is any integer that does not have p as a factor, then np-1 is equal to 1 mod p.
In other words, np-1 will always have a remainder of 1 when divided by p.
What is 232639 mod 13?
(Use Fermat's little theorem!)