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.

Monatomic elements have with ____ atoms in each per molecule.
three

Amphibians have ____ legs, and often look like reptiles.
four

Cigarette butts take ____ years to decompose and pose a fire hazard.

seven