Scientists work with really, really big numbers and also really, really tiny numbers. It becomes useful to have a short-hand way of writing these giant and teeny numbers so the numbers don't take up a whole page.

To express really big numbers, the scientific notation short-hand will use a positive exponent like 10¹¹.

To express really tiny numbers, the scientific notation short-hand will use a negative exponent like 10^-9.

Our certain galaxy might have 100 billion stars. 100 billion written in long-hand is 100,000,000,000. In scientific notation, it is written simply as 10¹¹.

10¹¹ is 1 with 11 zeros after it.

Remeber base numbers (b) and exponents (e)?

b^e means multiple b times itself e times.

10¹ = 10 (1 zero)

10² = 10 X 10 = 100 (2 zeros)

10³ = 10 X 10 X 10 = 100 (3 zeros)

10³ = 100

1 X 10³ = 100

In this case, the "1 X " doesn't really add much. Multiplying a number times 1 just gives you the same number.

However, our sun is in the Milky Way galaxy which has about 3 billion stars.

1 X 10³ = 1 billion and so 3 X 10¹¹ is 3 billion.

When you want to go from the short-hand scientific notation back to the long-hand form of the number you have to "bounce" the decimal place the correct number of place in the correct direction.

If the exponent is positive, you bounce the decimal place to the right by however many times the exponent says.

The width of double-stranded DNA is 2 nanometers, or 0.000000002 meters.

2 X 10^-9

If the exponent is negative, you bounce the decimal place to the left by however many times the exponent says.