This works because the distances from the `` 1 '' are proportional to the logarithms of the marked values : Operations may go `` off the scale ; '' for example , the diagram above shows that the slide rule has not positioned the 7 on the upper scale above any number on the lower scale , so it does not give any answer for 2 × 7 .
Operations may go `` off the scale ; '' for example , the diagram above shows that the slide rule has not positioned the 7 on the upper scale above any number on the lower scale , so it does not give any answer for 2 × 7 .