Scientific notation is all about decimals. Especially very big and very small decimals. Scientists deal with some very large numbers (like the distance of the Earth from the sun, 93,000,000 miles) or very small numbers (the diameter of an atom: about 0.00000003 centimeter). It is awkward to deal with numbers in this form (all those zeros!), so mathematicians (and scientists) developed a way to express these numbers without all those zeros. It involves exponents, specifically powers of 10.
Every time you move the decimal point to the right in a number, you are multiplying it by 10. Conversely, every time you move the decimal point to the left you are dividing by 10. If you move more than one place you are multiplying (or dividing) by powers of 10. If you move it 2 places to the right you are multiplying the number by 102 = 100. A number in scientific notation is of the form:
a x 10 n
the coefficient   a   is a decimal number between 1.0 and 10 and
n is an integer that says how many places to move the decimal, either right (+) or left (-).
So, that distance of the Earth from the sun, 93,000,000 miles, becomes 9.3 x 107
because you move the decimal point to the right 7 places to get the decimal number 93,000,000
That size of an atom, 0.00000003 centimeter, becomes 3.0 x 10-7 because you move the decimal point 7 places to the left to get its decimal representation 0.00000003
"how many places do I move the decimal point, and which way?"
Here is a table of some common numbers and their representation in both decimals and scientific notation:
Now here are a couple of problems for you: