倍數問題很令人困擾...

Shine-On

How long will it take for a sum of investment to grow to three times as much at a simple interest rate of 12.5% per year ?

a sum = 1 + three times = 4 ?

被一倍兩倍弄到很亂..1的1倍 = 2還是1?
                          1X1=1 or 1+1=2?

                         2的2倍  = 4還是6?
                         2X2=4 or 2+2+2=6?