 So now let's look at some other calculations here. We had started out in the last video with some simple calculations using some amount of current over some amount of time to figure out the charge. But a lot of times we're going to have some more interesting problems where we're going to have some small numbers and some metric prefixes. So maybe you're given a problem where you've got 2.4 microcoulombs divided by 60 nanoseconds. So we need to remind ourselves of what some of those metric prefixes mean. Microcoulomb means 10 to the minus 6th and nanosecond would mean 10 to the minus 9th second. So putting those values in here we would want to actually multiply out with the metric prefixes and we would end up having 2.4 times 10 to the minus 6th coulombs and 60 times 10 to the minus 9th coulombs. Remember if you've got things that have exponents on the bottom you're going to want to make sure you use your parentheses if you use the scientific notation. If you use the exponent button on your calculator you might be able to get away without using those parentheses but you're always safe putting them in. So when you put these in your calculator you should get something like 40 amps. Well you should get exactly 40 amps. If you're not coming up with that on your calculator again remember to put in your parentheses around your scientific notation. So now one more example here. We're going to go ahead and move a few of these things out of the way just so that we can have some space. What if instead of being given the amount of charge you're given the number of charges? We had an equation back in electrostatics that said if you've got a particular number of charge it's related to the amount of charge and what we called the fundamental charge the charge on a proton or an electron. And you could rearrange that equation to solve it for the amount of charge if you know the number of charges and of course E is a constant. This isn't the natural E, this is the fundamental charge E. So let's do an example like that. Let's say we're given a really large number something like 3 billion and so that's 1,000 million, billion, 3 billion and let's say there are electrons which is why I have the minus sign out front. And again that fundamental charge the charge on a proton or an electron is 1.6 e to the minus 19th coulombs and again this is the scientific exponent E. So you'd multiply that out and you're going to get a value of minus 4.8 e to the minus 10th coulombs and you can either leave it in that scientific exponent notation or you could put it into the engineering exponent in which case it would be minus 0.48 nanocoulombs. It's also equal to 480 picocoulombs if you wanted to put it into that metric prefix. So this is a way you can take a large number of electrons or protons and move them into something where you can actually find the charge. Now if I was going to end up working with something like this except I now want to actually find a current rate, let's say I take my number here and I make this the 0.48 nanocoulombs and now I want to do it in 0.5 nanoseconds. Again you could put that into metric prefixes. In this case since I have a nano on the top and the bottom I don't have to put it out into the metric units. I could just leave it this way and do my 0.48 divided by my 0.05 and that would give me a value of 9.6 and again the nano canceled with the nano my coulombs over seconds is going to give me amps. So I moved a small amount of charge but in a very small amount of time and that's going to give me a current of 9.6 amps. So these are just some other examples of ways that you can go through and do some calculations of currents where you've got some more interesting numbers with metric prefixes or you're actually given the number of electrons or protons.