TASK DEFINITION: Given a sentence, fill out the missing word with a 'no' or a number (between zero and ten). You should write the numbers with english alphabet, like: four instead of 4.
PROBLEM: Most species have four toes, ____ of which are forward-pointing.

SOLUTION: three

PROBLEM: Asbestos is a generic term used to describe the fibrous form of ____ different minerals.

SOLUTION: six

PROBLEM: Birds have ____ basic types of feathers.

SOLUTION:
three