 So we looked at standard form in this video, so you should already know how to write into and out of standard form. In this video, we're going to look at how to add and subtract and multiply and divide with standard form. So for adding and subtracting, there are no tricks. You just need to write the numbers out into ordinary numbers, do the calculation and then change the answer back into standard form. Simple! So let's not spend any more time looking at adding and subtracting and go straight onto multiplying and dividing. We use the rules of indices. If you aren't sure about what to do in multiplying and dividing with indices, watch this video first. Let's have a look at an example. We multiply 5.2 by 2 to get 10.4 and we add the powers of 10, so 5 add 3 is 8. 10.4 times 10 to the 8. But be careful! That answer isn't actually in standard form. 10.4 is above 10, so our answer isn't standard form. The correct answer is 1.04 times 10 to the 9. Some of you may easily be able to see that because we need to move the decimal place left one place from 10.4 to 1.04, so we add in an extra jump to the times 10. So it's times 10 to the 9. But if you're unsure, just write out into an ordinary number and then rewrite it back into standard form again. So dividing follows the exact same process. Give this question a go. Pause the video, work out the answer and click play when you're ready. Did you get it right? 4.3 times 10 to the power of 4. So there you have calculating with standard form. Adding and subtracting is really easy. We just write them out into ordinary numbers and then multiplying and dividing you do a numbers calculation and then an indices calculation. If in doubt write the number out into an ordinary number and then write it back into standard form to make sure you don't make any mistake.