THE Royal Australian Air Force has published a complicated maths formula online and asked job applicants to solve it if they want to apply for a position as an engineer.

The RAAF challenged engineers to solve the problem to find a phone number to call and apply for a job.

It hires aeronautical, airfield, armament and electronics engineers with Bachelor of Engineering qualifications, Business Insider reports.

Defence Force recruiters obtained the formula from a University of Melbourne professor.

But the maths problem - which involves infinite sums, integrals, complicated trigonometry and imaginary numbers - doesn't produce the RAAF recruitment phone number because of typos within the copy.

This is the published formula:

The first four terms in the formula produce the Defence Jobs phone number, 131901, when added together.

The remaining terms are intended to equal zero, but two typos have made that impossible:

The formula works if you replace sin2 x with sin (2x) in the third-last line, and (2k-1)! with (2k+1)! in the second-last line.

An Air Force marketing manager from Defence Force Recruiting took the twin typos in good humour.

"Our original formula included two small typos which we have now fixed," they said.

"We hope people still enjoy the inherent fun and hidden challenges. Our thanks go to the eagle-eyed Reddit users who spotted them first. You are exactly the sort of people we'd be looking for."

The Australian Defence Force puts job applicants through a two-day recruiting process, including interviews with a career counsellor, nurse, psychologist, doctor and military staff member.

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