Indices for 2nd Year

Make sure you understand the three rules for indices or powers. The Poweroint and a Summary can be downloaded below. The summary includes reciprocals and scientific notation. For the summer exam you should be able to do these when the base number is represented by a letter.

Be careful with powers of negative numbers. Learn these two examples - this is the way your calculator works.

Orders of Magnitude

There is a famous video which shows very large and very small objects called "Powers of 10", you can see a short version here or the original here.

To find the order of magnitude between two numbers follow these steps

• Both numbers must be written in scientific notation.
• Round off the first part to either 1 or 10, whichever it is closer to.
• Tidy up to just powers of 10.
• Subtract the smaller power from the bigger power - this is your answer (subtract the powers not the numbers).

If there is a very big difference between two numbers then normal rounding off is not very useful. The order of magnitude gives us a rough comparison. For example if the order of magnitude is 2 then one number is about 10² or 100 times bigger than the other. If the order of magnitude is 6 then one number is about 10⁶ or a million times bigger than the other.

Click the link for the PowerPoint used in class, you can view it on-line without any animations or download it to see the animations (it looks better!). Summary for Second Year.

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