Amount, distances and number can be taken as single units if used as subjects.
- Two is enough.
- Fifteen ringgit is what I have to pay.
- Sixteen kilometres is a long way to talk.
But,
- Two watches have been stolen from her locker. (2 units)
- There are 16 kilometres more to cover. (16 units of distance)
- There are 365 days in a year. (365 units).
