A=19911991199119911991.1991,(1991个1991),A除以13,余数是几用方程解,把过程写清楚

A=19911991199119911991.1991,(1991个1991),A除以13,余数是几用方程解,把过程写清楚
A=19911991199119911991.1991,(1991个1991),A除以13,余数是几
用方程解,把过程写清楚

A=19911991199119911991.1991,(1991个1991),A除以13,余数是几用方程解,把过程写清楚
1991 mod 13 = 2
19910000 mod 13 = 2*10000 mod 13 = 6
199100000000 mod 13 = 6*10000 mod 13 = 5
1991000000000000 mod 13 = 5*10000 mod 13 = 2
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1991 mod 3 = 2
x=((1991-2)*(2+6+5)+2+6) mod 13=1988 * 13 mod 13 + 8 mod 13 = 8