:00

+1 property

For any number n, n + 1 equals the next counting number after n.

:30

the digits after the colon when it is 30 minutes past the hour

[Answer: 16 L/day; 640 L total

plus water for the animals, which would have been enormous]

[Answer: 5 kg; 5,000 g

this uses the metric connection between liters and kilograms]

A = π × 4²

use the π button on the calculator

A and S are EQUAL priority

work left to right, whichever comes first.