0.64
this has to do with place value.....what place value is ur last digit (6) in ? It is in the hundredths place. so we put the 64 (without the decimal) over 100.
64/100 which reduces to 16/25. Its that simple.
Examples :
0.5....the last digit (5) is in the tenths place...so put it over 10.
5/10 reduces to 1/2.
0.225...the last digit (5) is in the thousandths place. 225/1000 reduces to
9/40