?????????????? "annum" ????????????
me assume this be KOMPOUND INTEREST
and start$=4000, kompound per YEER, 12% interest
yu want end$=start$+1200=4000+1200=5200$
kompound interest: end$=start$*(1.12)^n...n=num yeers
end/start=5200/4000=1.3...=1.12^n
log(1.3)=n*log(1.12)
n=log(1.3)/log(1.12)
n=0.11394335230683737 / 0.11332868530700327
n=1.005425264 yeers