We did some experiments with people using ordinary handheld calculators, doing sums from 4×-5 to harder ones like 2^-π.

We got surprising results.

A slip or an unnoticed oddity of calculation can cause disaster, from paying the wrong bills, getting the wrong dose of medicine, to throwing an aircraft off course. It is very important for everyone to be able to do mathematics accurately and easily! That only 27% of calculators got the correct answer is very worrying.

Try one of our problems on your own calculator: 4×-5 should be -20, though most calculators give you -1, because they do 4-5 instead.

• Try a simulation now!

If you have a scientific calculator, see what results you get for 2^-π, which should be 0.113315.