1
00:00:00,000 --> 00:00:04,000
The φ(831) equals 552.
2
00:00:04,000 --> 00:00:06,000
We can calculate this by seeing that
3
00:00:06,000 --> 00:00:10,000
831 = 277 * 3
4
00:00:10,000 --> 00:00:12,000
and 277 and 3 are both prime.
5
00:00:12,000 --> 00:00:19,000
We showed in lecture the φ(pq) = (p - 1)(q - 1).
6
00:00:19,000 --> 00:00:25,000
And so the totient of 831 = 276 * 2
7
00:00:25,000 --> 99:59:59,999
which equals 552.