Most of us have come across numerical reasoning tests, usually in the application stages when applying for a job. Numerical reasoning tests are challenging as they require you to solve mathematical problems under a strict time limit.

But what is the hardest numerical reasoning question ever written?

We scoured through thousands of tests to find the one question that the fewest people could answer correctly. Have a go and see if you can be one of the few who can answer it.

If the rates change in 2025 by the same amount as in 2024 and manufacturing costs do not change, what will the manufacturing cost be in Brazilian Reals?

A) 10.83
B) 11.83
C) 12.83
D) 13.83


The correct answer is C) 12.83.

Step 1. Brazilian Reals changed by 0.05 between 2023 and 2024. Therefore, the rate will move from 2.80 to 2.85 in 2025 .

Step 2. Calculate manufacturing cost in Reals = 2.85 X 4.5 = 12.83


Of 478 takers, 158 got it correct, and 320 got it wrong. That’s a paltry 33% success rate.

So there you go: the hardest numerical reasoning question of them all. Bear in mind that 33% would have got it by chance alone!

If you’d like to get questions like this right, it might be time to start practicing numerical reasoning questions.