3tenths multiplied
by 100 equals

0.3*100. All you have to do is multiply 0.3 by 10 (3) then multiply that number by 10. Or you can do it like this: add two zero's to the end of the number, and get rid of the decimal after you add one zero. So this is what it would look like : 0.3, 3.0 30.0. all you are doing is moving the number 3 up by 1 digit each time you add another 0 to the end.