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# How important is it to remember maths formulas watch

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1. I am going through the CGP maths GCSE books and it says to remember the formula N = N0(1+r/100)n. No maths teacher has ever told me to remember it, is it really necessary to learn? Also I can answer compound interest questions without this. Thanks
2. U dont need to learn that... ive never seen that formula till now and most of the complicated equations that u need to know are on the first page
3. You may have to remember it, however, once you do a couple of questions on that topic (Compound growth and decay I believe it is), you'll think there never was a formula for it. It looks quite complex but it's really not.
4. If, given a problem like you have £20 in the bank and you get 30% interest at the end of the year (does such a bank exist? ), I suspect that your method to find the amount you have at the end of the nth year would be to find 30% of 20, then add it on, find 30% of the new amount and then add it on until you reach the nth payment.

Finding 30% of 20 is the same as doing (30/100) * 20, and then you are adding this on to the original amount, which is 20. If you were to make this look better, this would be 20(1 + (30/100)), which is the same as N0 (N0 meaning the amount you start with) * (1 + r/100), where r is the interest rate, 30%.

You can find the amount at the end of the next year as well by multiplying N0(1-(r/100)) (which is 20 *(1-(30/100))) by multiplying, and this is just a much faster way of doing it.

Have a look at past papers for your exam and see which way they prefer you to use it.

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Updated: May 2, 2016
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