Suppose a man's scalp hair grows at a rate of 0.35mm per day. what is this growth rate in feet per century?

First off, let's find out the growth rate per century in millimeters. 
Since there are are one hundred days in a century, we just have to multiply 0.35 by 100. We just have to move the decimal point two places to the right to receive a rate of 35 mm per century. We can use a mm to ft conversion calculator to convert 35 mm to feet- getting 0.1 (rounded to the nearest tenth.
So this growth rate is 0.1 feet per century. Hope that helped!