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Evaluate mentally.
Have you played the game of war with a deck of playing cards?
Your teacher will give you and your partner a set of special cards.
Let the logarithm war begin!
Sometimes it’s possible to find an exact value for a logarithm. For example because , and . Similarly, because .
Often it is not possible to find an exact value, but using number sense allows us to get a reasonable estimate. Let’s say we want to find that makes true.
We can first express as . Then, because 980 is between and we know that must be between 2 and 3.
But where does lie between 2 and 3? Because 980 is much closer to 1,000 than it is to 100, is likely a lot closer to 3 than it is to 2. This means that 2.9 would be a better estimate than 2.1 would be.
We can use a calculator to verify our estimate and find that is about 2.99.