three tenths of one percent = 1% x (3/10) as written in fraction: 3/10 = 0.3, therefore: 1% x 0.3 = 0.3% or 0.003 (in decimal figure). :)

Hello Shen, 1 % = 0.01 three tenths = 0.3 three tenths of one percent = 0.3 divided by 0.01 = 30

I've seen this same situation about 100 times as an engineer. If you use the % sign, then 0.3% is correct. If you specify 0.003, you might want to put a comment to the side saying either "0.03 = 3.0%" or "0.01 X %". It is important that all parties using the number understand what units they are dealing with. To answer you simply, either is correct, so long as the units are clear to everyone.

Sorry I made a mistake . Romulus's answer is the correct one. I got mixed up. It is 0.3 multiplied by 1 % not divided!