二三の實例は必ずしも蛇足ならじ.
b = 3 {\displaystyle b=3} 又は b = 9 {\displaystyle b=9} , 10 ≡ 1 ( mod 3 ) ( mod 9 ) c = 1 {\displaystyle 10\equiv 1{\pmod {3}}{\pmod {9}}\quad c=1}
b = 11 {\displaystyle b=11} , 10 2 − 1 = 99 = 9 × 11. c = 2 {\displaystyle 10^{2}-1=99=9\times 11.\quad c=2}