Meaning trap
work out
solve or understand
to find the answer to something by thinking or calculating; to understand something after considering it.

Don't mix these meanings
Same phrase, different job.
to find the answer to something by thinking or calculating; to understand something after considering it.
Another meaning of 'work out' is 'exercise'; compare the examples to keep the meanings separate.
Hear it in context
Notice where the phrase sounds natural.
It took me a while to work out the answer to the math problem.
In my opinion, it's important to work out solutions to problems independently before asking for help.
Fix the pattern
One small grammar move makes it sound right.
Not: I can't work out this.
Say: I can't work it out.
With a pronoun, the object goes in the middle: 'work it out'.
Which sounds natural?
Tap the one a native speaker would say.
'Work out' is the everyday verb for figuring something out. 'Calculate the total amount required' is fine in writing but stiff in speech.
Build natural chunks
Words that usually travel with it.
work out + answer
- the cost
- a solution
- why
- how to do it
Don't confuse it
Related
Other meanings and phrases to compare.
- work out (exercise) — Another meaning of 'work out' is 'exercise'; compare the examples to keep the meanings separate.