Casio calculators allow the user to program an effective tax rate into the calculator.

This is used to quickly calculate taxes on given amounts.

The effective tax rate is a hypothetical rate that shows the percentage of income that is taxed if there was only one tax rate. For example, if a company makes £65,000 and pays £22,750 in taxes, then their effective tax rate is 35 per cent.

Press "AC."

Press and hold "SET/%" for two seconds.

Press "TAX+."

Enter the tax rate.

Press "SET/%."

Turn the calculator to "Print" mode.

Press "CA."

Press and hold the "SET/%" button for three seconds.

Enter the tax rate.

Press "TAX+," then press "SET/%."