Multiplying numbers in scientific notation extends what we do when we multiply regular decimal numbers. For example, one way to find  is to view 80 as 8 tens and to view 60 as 6 tens. The product is 48 hundreds or 4,800. Using scientific notation, we can write this calculation as  

To express the product in scientific notation, we would rewrite it as  .

Calculating using scientific notation is especially useful when dealing with very large or very small numbers. For example, there are about 39 million, or residents in California. The state has a water consumption goal of 42 gallons of water per person each day. To find how many gallons of water California would need each day if they met their goal, we can find the product , which is equal to . That’s more than 1 billion gallons of water each day.

Comparing very large or very small numbers by estimation also becomes easier with scientific notation. For example, how many ants are there for every human? There are ants and humans. To find the number of ants per human, look at . Rewriting the numerator to have the number 50 instead of 5, we get . This gives us . Since is roughly equal to 6, there are about or 6 million ants per person!