In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[Q]: Sewage travels through _ different sets of pipes.
[A]: three

[Q]: Coral reefs make up only _ per cent of the area of the Great Barrier Reef.
[A]: five

[Q]: Infectious spores can live for up to _ weeks on contaminated objects.
[A]:
eight