1. Astronomy has really big numbers

2. Distance between Earth and Sun
meters
kilometers
This is the closest star.

3. Distance To Next Closest Star
Alpha Centauri
kilometers Or
meters
Too big. Mind explosion.

4. What’s a better way?
× 1013 km Or
4.365 light years

5. Scientific Notation 2.75 x 103 A number is written in two parts:
Just the digits (with the decimal point placed after the first digit),
× 10 to a power
Example:
2.75 x 103

6. x 103 = ????????
× 10 to a power puts the decimal point back where it should be
(i.e. it shows how many places to move the decimal point).
Examples:
2.75 x 103 =

7. Another Example

8. How to do it Step 1 To figure out the power of 10, think
"how many places do I move the decimal point?"

9. How to do it Step 2 If the number is 1 or greater
the decimal place has to move to the left
the power of 10 will be positive.  
If the number is smaller than 1
then decimal place has to move to the right
the power of 10 will be negative: 

10. Example 0.0055 would be written as 5.5 × 10-3 Because
= 5.5 × = 5.5 × 10-3

11. Why not just write the number?
Scientific Notation is used for numbers that are
HUGE or tiny
For example it is easier to write (and read)
1.3 × 10-9
Than

12. Which one is easier to read?
So what do you think?
The distance from the earth to the sun
meters
kilometers or
1.50 x 1011 m
Which one is easier to read?