When the top number (numerator) is half of the bottom number (denominator) the fraction is a half.
When the top number (numerator) is one-fourth of the bottom number (denominator) the fraction is a quarter.
1/2 = 2/4 3/6 4/8 5/10 6/12 7/14 10/20
1/4 = 2/8 3/12 4/16 5/20 6/24 7/28 10/40