MARY L. CROWLEY, KENNETH A. DUNN, On Multiplying Negative Numbers, The Mathematics Teacher, Vol. 78, No. 4 (APRIL 1985), pp. 252-256 ...

Revise how to add, subtract, multiply and divide negative numbers using the correct order of operations (BIDMAS) and how to work this out on a calculator.

The Ancient Greeks rejected negative numbers as absurd, by 600 AD, the Indians had written the rules for the multiplication of negative numbers and 400 years later, Arabic mathematicians realised the ...