four equal parts, - 

each part is one-quarter.

two equal parts, - 

each part is one-half.

three equal parts, - 

each part is one-third.

$$ \frac{1}{2} $$ of 18 = - 

9

$$ \frac{1}{2} $$ of 12 = - 

6

$$ \frac{1}{2} $$ of 16 = - 

8

$$ \frac{1}{2} $$ of 14 = - 

7

$$ \frac{1}{2} $$ of 20 = - 

10

$$ \frac{1}{2} $$ of 10 = 5 - 

5 = $$ \frac{1}{2} $$ of 10

$$ \frac{1}{2} $$ of 20 = 10 - 

10 = $$ \frac{1}{2} $$ of 20

$$ \frac{1}{2} $$ of 14 = 7 - 

7 = $$ \frac{1}{2} $$ of 14

$$ \frac{1}{2} $$ of 18 = 9 - 

9 = $$ \frac{1}{2} $$ of 18

To find one-third of a number, - 

you divide the whole into 3 equal parts.

To find one-quarter of a number, - 

you divide the whole into 4 equal parts.