So here we're gonna talk about the calculations that we have to employ in order to deal with uncertainties when it comes to addition subtraction, multiplication and division. Now these are all related to random error. Of course when it comes to our calculations. So here we're gonna say with addition and subtraction or multiplication and division, we will use certain rules for propagation of our answer here. We're gonna use what's called the real rule. The real rule says that the first digit of the absolute uncertainty is the last significant digit in the answer. What does that say? So for example, let's say we had Absolute uncertainty of .0005 And we had a number a measurement of 7.95,. Here the first digit in the absolute uncertainty. That is significant. Is that five? What does it occur? It occurs in the fourth decimal place. That would mean that my measurement has to have four decimal places within it. So here are four decimal places here because there's a six year, I'd have to round this number up. So the measurement here would be 7.9588. So the 7.9588 plus or minus 0.5. As our measurement with its absolute uncertainty, we'll do another one. Let's say that our absolute uncertainty here was 0.1. And let's say that we had 13.2 35. So here our first digit in the absolute uncertainty. That's significant is that one? It's in the first decimal place that means our measurement has to have one decimal place. So here's our decimal place because this number here is a three. We wouldn't do anything to that too. So this comes out to 13.2 plus or minus 0.1. So when we're doing these propagation of our answers, we have to keep this in mind when we're dealing with addition, subtraction, multiplication or division when it comes to the measurement with the absolute uncertainty. Now here, if we take a look at addition and subtraction, we'll learn all the different ins and outs in terms of the calculations necessary to get our correct answer. But remember always rely on the real rule, click on the next video to see me go through this particular example when it comes to addition and subtraction.