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.

Differentiation is caused by the energy going in ____ directions.
two

Natural ytterbium is a mixture of ____ stable isotopes, with seven other unstable isotopes known.
seven

Panther chameleons reach sexual maturity at a minimum age of ____ months.

seven