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.

Q: Variable stars fall into ____ major physical classifications.

A: four
****
Q: Tin exists in ____ allotropic forms.

A: three
****
Q: Normal cats have five front toes and ____ back toes.

A:
four
****