Dear Bill, I tried this: (%i1) log10(x):=log(x)/log(10); (%o1) log10(x):=log(x)/log(10) (%i2) solve(y=log10(x),x); (%o2) [x=%e^(log(10)*y)] Which gets you a bit closer, but I didn't find a way to simplify this to x=10^y Can someone help with this? Best regards, Michael