## Solution

To convert from microinches to inches, use the relationship between inches and microinches, that 1 inch = 1000000 microinches.

Because of this relationship, we find that converting from microinches to inches is simply a matter of dividing the number of microinches by 1000000.

## Applications of Microinches

Now we know how to convert microinches to inches, but with this measurement being so small, you may wonder how there would ever be a use for it. You would be surprised! Microinches can be used in medicine, engineering, entomology, and many other areas.

In medicine, very tiny bacteria, viruses, and other organisms are studied, many of which are too small to detect with the human eye. If we could see viruses and bacteria with our eyes, we would be much less likely to get a cold or the flu, because we would simply wash the virus off of our hands before it had a chance to make contact with a mucus membrane. To put this into perspective, let's consider an example: On average, the flu virus is about 3.937 microinches in diameter. To convert this to inches, we divide by 1000000 to get 3.937 / 1000000 = 0.000003937.

This tells us that on average, the flu virus is 0.000003937 inches in diameter. That's so tiny! There's no way we could detect that with our eyes. No wonder it's so important to wash your hands often during cold and flu season!

To really appreciate how tiny this measurement is, let's consider another application of when it is useful to be able to convert microinches to inches. In engineering, there is something called surface finish. This is basically the measurement of surface roughness. For instance, the surface finish of a car would tell how smooth the car's finish is. I don't know about you, but if I'm buying a new car, I would want that surface finish to be as smooth as possible - meaning, I would want the surface finish to be as small as possible. The surface finish of a car would probably run anywhere from 200 to 400 microinches.

Again, that's hard to picture, so let's convert both of those values to inches by dividing by 1000000 to get a better idea.

We see that 200 microinches = 0.0002 inches, and 400 microinches = 0.0004, so the surface finish of a car runs between 0.0002 inches to 0.0004 inches. We can see why any surface roughness would be very hard to identify on a car's surface, when the car is in good shape.

Microinches are used in any area that involves very small particles or measurements. Being able to convert microinches to inches gives us a better idea of just how small this measurement really is. Thankfully, this conversion is as simple as dividing by 1000000!