Instruments are tricky to make and maintain. Unless there is a huge error in them it is very difficult to realize that something is wrong with them. For example, the weighing machine at your grocer has a slight error. It shows 1 kg of rice as 1.050 kg. Unless you are taking a huge quantity of rice, that error will never be caught by you or the grocer for that matter. Most of the gadgets and appliances we use are commercially mass built. Approximation is inherently built in them. Accuracy is always given a second priority in them. Let’s take a look at some of the gadgets you use every day that are not as reliable as you think they are. Cellphones lie about how much charge they hold Your phone never charges to a 100 percent. Because a fully charged battery degrades faster. That’s why the phones actually only charge until 95% and stop. But the phones cannot show you that it has charged only 95%, because then you will never plug it out. But it is for the phone’s safety, so chill out.

Almost 40% of the Blood pressure cuffs are faulty in readings.

Have you ever noticed that if your blood pressure came a bit high, your doctor calls you for another reading the next day. But that does not matter because it may be because the instrument itself is faulty.

And if the instrument shows the blood pressure a few points below that it actually is, it is endangering a number of people who have high blood pressure because their readings will always be shown normal.

Always ask your doctor to show the calibration certificate of the cuff before getting your blood ressure measured.

Speedometers have error too.

Although this is not exactly a problem in India, since the cops here do not have a digital speedometer that can be used to detect if you are speeding or not.

But this is not a big issue because the errors are not that large and unless you are driving a Bugatti with one of the faulty speedometers, you should be fine.