# Giant Slide Rule

Until electronic calculators became available, the slide rule was a convenient, inexpensive and portable aid for multiplication and division calculations. Powers, roots and trigonometrical functions could also be carried out, but not, unfortunately, the simpler operations of addition and subtraction. Consequently, calculations which used a mix of operations – such as applying the cosine rule – were cumbersome and also required some work on paper. Accuracy was limited to about 3 significant figures: not quite as accurate as four-figure logarithm tables.

On the plus side, they were robust and didn’t need batteries, and the user had to be able to estimate the answer mentally in order to place the decimal point, a skill which some feel has been lost with the advent of electronic calculators.

The giant example in the Mathematics Department allowed a teacher to demonstrate the uses of the slide rule to whole classes.

Peter O’Grady, WS Staff 1975-