數學 .. 緊急

log 50^40
= 40log50
= 40 log (100/2)
= 40 (log 100 - log 2)
= 40 (2 - 0.3010)
= 40 * 1.699
= 67.96
所以 10 ^ 67.96 = 50^40
而10 ^ 67.96共有 68 位數 , 所以50^40 是 __68__ 位數 .
(具體些 :
10^1.96 = 91.20108.....(兩位)
10^2.96 = 912.0108.....(三位)
10^3.96 = 9120.108.....(四位)
...............................................
10^67.96 = (68位)