0.81的循环(默认81为循环节):
0.81818181…81…
=0.81 + 0.0081 + 0.000081 + … + 0.0…081 + …
=[0.81(1-0.01)^n]/(1-0.01)(n→∞)
=0.81/(1-0.01)
=81/99
=9/11
0.81的循环(默认81为循环节):
0.81818181…81…
=0.81 + 0.0081 + 0.000081 + … + 0.0…081 + …
=[0.81(1-0.01)^n]/(1-0.01)(n→∞)
=0.81/(1-0.01)
=81/99
=9/11