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.

Marine biologists have ____ theories on why whales breach.
two

Red pandas have ____ toes that are widely separated and semi-retractable claws.
five

Most infants double their birth weight in ____ months and triple it in a year.

six