Writing 0.000000000000000000160217663 is an invitation to miscount the zeros, and nobody reads it faster than 1.602 × 10⁻¹⁹. Scientific notation separates the digits that carry information from the size of the number, so two quantities can be compared at a glance by their exponents alone.

Using it in three steps

1. 1 Type into whichever box you already have filled - the other one follows automatically.
2. 2 For scientific notation, put the digits in the left box and the power of ten in the right one.
3. 3 Check the three results underneath: standard form, engineering form and how many figures you actually gave.

Standard form and engineering form

Standard form keeps the leading digit between 1 and 10, so 47 000 becomes 4.7 × 10⁴. Engineering form instead keeps the exponent to a multiple of three, giving 47 × 10³, because that is where the prefixes live: kilo, mega, giga, milli, micro. If your answer is going to be spoken or labelled on a component, the engineering line is the one you want.

Significant figures are about the digits, not the value

0.5 and 0.500 are the same number but not the same measurement: the second claims accuracy to a thousandth. That is why this converter counts the figures from what you typed rather than from the value it computed. If you paste 2.30 you get three; if you paste 2.3 you get two, and the difference is a real claim about your instrument.