Once you start to read datasheets and schematics, you run into scientific notation and metric prefixes of values. Engineers use their own flavor of scientific notation, called engineering notation. It’s based on the metric system and easy to use.
If you deal with very large or small numbers, you quickly run into notational obstacles. For instance, numbers can be much too large or small to write down. Furthermore, they can be hard to read that way. Finally, it can be very easy to make a mistake using fully written out numbers.
So scientists came up with a generic way to express numbers. Scientific notation uses the following rule set:
- Move the decimal after the first digit. Remember the number of moved places.
- Drop the zeros. This leaves us with a coefficient greater than 0 and smaller than 10.
- Write down the exponent with the number of moved places.
If we take a large number as an example:
With decimal numbers, we get a negative exponent. The concept remains the same though:
How does engineering notation differ?
While scientific notation is easy to grasp engineers use it a little bit different. First of all, they based engineering notation on the metric system, especially using metric prefixes like kilo, micro, or nano.
As a result, the exponent of 10 must be divisible by the number three. So we get exponents to the power of 3, 6, 9, -3 etc. Consequently, we end up with a coefficient larger than 0 and smaller than 1000.
In the table below we put it all together. Here you find the metric prefixes from the International System of Units (SI) widely used in electronics.
Because of the division by three, we now can easily translate between metric values. For instance, both notations below express the same value of a resistor: