Find somebody with a tach on a tune-up tester or a timing light, and compare readouts. So far as the comment about 3 number bands and a multiplier, I've never seen one like that, and I've been doing electronics work since the mid-1960's, for Uncle Sam and a few other employers. It might be possible, but you're more likely to find a chicken with lips!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!