TASK DEFINITION: In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
PROBLEM: Frozen grafts can have a shelf life of up to _ years.

SOLUTION: five

PROBLEM: Many people spend _ or more hours a day working for someone else.

SOLUTION: eight

PROBLEM: World history is presented as _ discrete periods, from pre-history to the present.

SOLUTION:
six