Scientific Notation
Scientific Notation (also called Standard Form in Britain) is a special way of writing numbers:
Like this:  
Or this: 
It makes it easy to use big and small values.
OK, How Does it Work?
Example: 700
Why is 700 written as 7 × 10^{2} in Scientific Notation ?
Both 700 and 7 × 10^{2} have the same value, just shown in different ways.
Example: 4,900,000,000
1,000,000,000 = 10^{9} ,
so 4,900,000,000 = 4.9 × 10^{9} in Scientific Notation
The number is written in two parts:
 Just the digits (with the decimal point placed after the first digit), followed by
 × 10 to a power that puts the decimal point where it should be
(i.e. it shows how many places to move the decimal point).
In this example, 5326.6 is written as 5.3266 × 10^{3},
because 5326.6 = 5.3266 × 1000 = 5.3266 × 10^{3}
Try It Yourself
How to Do it
To figure out the power of 10, think "how many places do I move the decimal point?"
If the number is 10 or greater, the decimal point has to move to the left, and the power of 10 will be positive.  
If the number is smaller than 1, the decimal point has to move to the right, so the power of 10 will be negative: 

Example: 0.0055 would be written as 5.5 × 10^{3}
Because 0.0055 = 5.5 × 0.001 = 5.5 × 10^{3}
Example: 3.2 would be written as 3.2 × 10^{0}
We didn't have to move the decimal point at all, so the power is ^{}10^{0}
But it is now in Scientific Notation
More Examples:
Check!
After putting the number in Scientific Notation, just check that:
 The "digits" part is between 1 and 10 (it can be 1, but never 10)
 The "power" part shows exactly how many places to move the decimal point
Why Use It?
Because it makes it easier when you are dealing with very big or very small numbers, which are common in Scientific and Engineering work.
Example: it is easier to write (and read) 1.3 × 10^{9} than 0.0000000013
It can also make calculations easier, as in this example:
Example: a tiny space inside a computer chip has been measured to be 0.00000256m wide, 0.00000014m long and 0.000275m high.
What is its volume?
Let's first convert the three lengths into scientific notation:
 width: 0.000 002 56m = 2.56×10^{6}
 length: 0.000 000 14m = 1.4×10^{7}
 height: 0.000 275m = 2.75×10^{4}
Then multiply the digits together (ignoring the ×10s):
2.56 × 1.4 × 2.75 = 9.856
Last, multiply the ×10s:
10^{6} × 10^{7} × 10^{4} = 10^{17} (easier than it looks, just add 6, 4 and 7 together)
The result is 9.856×10^{17} m^{3}
It is used a lot in Science:
Example: Suns, Moons and Planets
The Sun has a Mass of 1.988 × 10^{30} kg.
It would be too hard for scientists to have to write 1,988,000,000,000,000,000,000,000,000,000 kg
Play With It!Use Scientific Notation 
Engineering Notation
Engineering Notation is like Scientific Notation, except that you only use powers of ten that are multiples of 3 (such as 10^{3}, 10^{3}, 10^{12} etc).
Example: 19,300 would be written as 19.3 × 10^{3}
Example: 0.00012 would be written as 120 × 10^{6}
Notice that the "digits" part can now be between 1 and 1,000 (it can be 1, but never 1,000).
The advantage is that you can replace the ×10s with Metric Numbers. So you can use standard words (such as thousand or million) prefixes (such as kilo, mega) or the symbol (k, M, etc)
Example: 19,300 meters would be written as 19.3 × 10^{3} m, or 19.3 km
Example: 0.00012 seconds would be written as 120 × 10^{6} s, or 120 microseconds