QYQ math

The question is from QYQ MATH::

on a certain scale of intensity, each increment of 10 in magnitude represennts a ten fold invrease in intensity. on this scale, an intensity corresponding to a magnitude of 165 is how many times an intensity corresponding to a magnitude of 125?

the answer list the calculation steps10*(165-125)/10, but =10000, then choose the answer

why? it should be 40, right? thanks

the expression was wrong, it should be 10^[(165-125)/10]=10^4

tenfold increase means increase by 10 times