（9+9²+9³）×0.01
= 9×(1+9+9²)×0.01
= 9×(10+81)×0.01
= 9×(90+1)×0.01
= 9×90×0.01 + 9×1×0.01
= 9×9×0.1 + 9×0.01
= 8.1 + 0.09
= 8.19