47. A  320 20 20 A A A  20 .1000000 A  20 .1000 A  20 A  20 ...

1.47. a  3

20 20 20 a a a  20 .1000000 a  20 .1000 a  20 a  20 .1001001 7 a 

  (vì 1001001 7  )

20 a 7

 ^{200 a}  ^{7 196}  ^{a 4 7}   ^{a 4 7} 

          , vì 196 7 

3

  a