Example of
using Units as a check

If someone says:

The time it took me to walk to class today was 10 minutes.

the number could possibly be wrong, but the statement at least makes sense.

The time it took me to walk to class today was 10 minutes.

the number could possibly be wrong, but the statement at least makes sense.

If someone says:

The time it took me to walk to class today was 10 kilograms.

something is obviously wrong.

The time it took me to walk to class today was 10 kilograms.

something is obviously wrong.

When you use a formula to calculate some answer you
can treat units just like
numbers multiplying and canceling them.

The units you are left with MUST be those which match
the ones expected or you have
made some mistake.