Writing very big and very small numbers
The distance to the sun is about 149,600,000 kilometers. A red blood cell is around 0.000007 meters wide. Counting zeros in numbers like those is slow and easy to get wrong. Scientific notation fixes that.
A number is written as a value between 1 and 10 times a power of ten. So 149,600,000 becomes 1.496 x 10^8, and 0.000007 becomes 7 x 10^-6. The calculator converts both ways and does arithmetic on them.
What the exponent tells you
A positive exponent says how many places the decimal moves to the right. A negative one says how many places it moves left. 10^3 is 1,000, and 10^-3 is 0.001.
To write a number in this form, move the decimal until one non-zero digit sits in front of it. Count the moves. That count is your exponent. Move left, it's positive. Move right, it's negative.
Multiplying and dividing
Multiply the front numbers and add the exponents. (3 x 10^4) x (2 x 10^5) is 6 x 10^9. If the front number goes past 10, fix it. (5 x 10^3) x (4 x 10^2) is 20 x 10^5, which becomes 2 x 10^6.
For division, divide the front numbers and subtract the exponents. (8 x 10^7) / (2 x 10^3) is 4 x 10^4.
Addition and subtraction are fussier. The exponents have to match first. The tool handles that step and shows the result.
Scientific versus engineering notation
Engineering notation is a cousin. The exponent is always a multiple of three, so it lines up with units like kilo, mega, milli and micro. 4.7 x 10^4 ohms becomes 47 x 10^3, or 47 kilohms. It's popular with electricians and engineers for that reason.
Scientific notation is more common in school and research. Use whichever fits your field.
Why bother
It keeps big numbers readable. It shows how many significant figures you really have. And calculators and programs use it internally, with an e in the middle: 1.5e8 means 1.5 x 10^8. If you see that in a spreadsheet, now you know.
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