How do I use the slide rule on my Casio watch?
A circular slide rule can be used for any multiplication or division problem. All you have to remember is that it is set up in ratios. So if you want to figure out what 10/5 is all you have to do is slide the 10 around so that it is over the 5 then go around until you find out what is over the top of the 1. There you will find, no surprise here, a 2. But wait!! What if you want to divide 1000 by 5? Just drop some zeros, do the sliding and then don’t forget to add them back to your answer. So it’s a good idea to do some rough mental math so that you have an idea of what the answer should be. Then you can use the watch to get the exact answer. If you want to do a speed/time problem like how long will it take me to travel 50 miles at 25 mph simply put the speed you are traveling over the 60 (or 6 depending on your slide rule). Then find the number under the 5 (or 50) and that will be the answer in minutes. Again, apply the “reason filter” and adjust. You’ll probably find a 12 in this case
