The square root of four twenty-fifths, is two fifths, because of the fact that the square root of four is two and the square root of twenty-five is five.
8.6 is rounded to nine because the number after the decimal is greater than four, so the number is rounded higher. If the number after the decimal is five or greater, the number rounds up. If the number after the decimal is four or less, then the number rounds down.
Four hundred ninety five thousandths.
Four and twenty-five hundredths in decimal form is 4.25
Expressed as a decimal, this is equal to 104.5.