①16的200次方除以13的余数是9.
16^200 | 13
= (13+3)^200 | 13
= 3^200 | 13
= 27^66 * 3^2 | 13
= (26 + 1)^66 * 9 | 13
= 1^66 * 9 | 13
= 9 | 13
= 9
②
(356 - 201) | 31
= 155 | 31
= 31*5 | 31
= 0
因此356 和201对于模31同余
(474 - 125)| 31
= 349 | 31
= 31*11 + 8 | 31
= 8 ≠ 0
因此474和125对于模31不同余
③
879 * 4376 | 11
= (869+10) * (4367 + 9) | 11
= (79*11+10) * (397*11 + 9) | 11
= 10*9 | 11
= 2
上面的“|” 表示求余.