Have you got a good scientific calculator to check through your answers? That’s a good start.

If you’re struggling with indices, you might try writing the whole number down so you can see the ‘wood for the trees’.

So 4.3 x 10^4L will be 43000 L

This is another way of checking your answers once you’ve figured it out.

10^4 is the same as 10x10x10x10 which is 10000, multiplying your 4.3 by this gives 43000 as above.

The EXP button on your calculator is the 10^ button. Press EXP then put in the index number.

There is more help here about the laws of indices:

http://www.mathsrevision.net/gcse/pages.php?page=2

For the second question, it’s a good idea to write down the actual numbers so you can get used to what they actually mean. It’s so easy to get blinded by numbers and forget they’re there to work for you :o)

A negative power is the same as 1/the positive power of the number.

So 10^ -4 = 1 / 10^4 = 1/10000 = 0.0001

So, question 2:

(3.6 x 0.0001) + (3.6 x 0.01)

= 0.00036 + 0.036

= 0.03636

Now, multiply this by 10^2 (Remember 10^2 is 10×10 = 100) so you have a tidy number…..

= 3.636 x 10^-2

As a rule, you can only be as accurate as the least accurate figure in the calculation, so in theory you should round this down to:

3.6 x 10^-2