The number four.
12 will divide into it evenly with no remainder.
Because 4 is the largest number that will divide into both of those numbers evenly, with no remainder.
12/24 is the same as 1/2. To simplify a fraction you have to find the largest number that you can divide both the numerator and the denominator by evenly. In this case, that number is 12 because you can divide both 12 and 24 by 12. Once you divide, your new answer is 1/2.
The Least Common Multiple (LCM) is the smallest number that two or more numbers will divide into evenly and 12 is the smallest number that both 4 and 6 divide into evenly.
9 over 12 reduces to 3 over 4. Divide the denominator (12) and the numerator(9) by 3 because 3 is the largest number that goes evenly into both numbers.
2 is the largest number that divides into both evenly.
Because 240 is the smallest number that 12, 16 and 20 will divide into evenly with no remainder.
Because 60 is the smallest number that both 12 and 20 will divide into evenly.
Because 12 does not divide into 124 evenly.