Fractions of whole numbers
To find a fraction of a whole number (for example $3/4$ of 12), we can use a simple idea: a fraction of a number means that we divide the number into equal parts and then take some of those parts.
For example, finding half of a number means dividing it by 2. So half of 12 is:
This also helps us understand phrases like increase by a half and decrease by a half. If we increase 12 by a half, we first find half of 12, which is 6, and then add it:
If we decrease 12 by a half, we again find half of 12, but this time we subtract it:
The same idea works for other fractions too. For example, if we want to find one quarter of 12, we divide 12 into 4 equal parts:
So $1/4$ of 12 is 3. If we want $3/4$ of 12, we take three of these quarters:
Mathematically, finding a fraction of a whole number is really the same as multiplying by the fraction. So:
This works because multiplying by a fraction means: divide by the denominator and take the number of parts shown by the numerator. So a fraction of a whole number is just a special kind of multiplication.
