After a birthday party,

1/3 of a large cake was left. If this piece of cake was shared equally among the 4 people, what fraction of the whole cake did each person receive?

Divide 1/3 by 4. To do this, convert four into a fraction (4/1). Then, take fours reciprocal (1/4) and multiply. One times one is one. Four times three is twelve. So each friend gets 1/12 of a cake.