 Hello and welcome to the session. In this session we will discuss how to use US and metric rulers to measure length. First of all we shall discuss how to use US ruler to measure length. Before learning how to read this ruler you must know the symbols used for representing inch that is this symbol and representing feet that is this symbol. While reading this ruler you should have a good knowledge of fractions. In US a standard ruler is divided into inches and feet. There are 12 inches in one foot. The inches unit is subdivided into number of lines that are of different lengths. In an inch the longest line in the middle marks the half inch and there is only one such line in an inch. There are two one quarter of an inch that is one by four inches which are represented by next shorter line in an inch. Here in this ruler these are represented by one by four and three by four. There are four shorter lines that mark one eighth of an inch that is one by eight inches and these are one by eight, three by eight, five by eight and seven by eight. And there are eight shortest lines that mark one sixteenth of an inch that is one by sixteen inches and these are given by one by sixteen, three by sixteen, five by sixteen, seven by sixteen, nine by sixteen, eleven by sixteen, thirteen by sixteen and fifteen by sixteen. In some rulers they extend to represent one by thirty two inches mark on ruler. But in most typical rulers the smallest measurement unit is set to one by sixteen inches. Counting the distance in an inch there are sixteen lines that represent an inch to be sixteen by sixteenth long. However in order to avoid complicated measurement we often express the fractional units into its largest unit hence an inch. Therefore when you have eight lines which basically represent the unit of eight by sixteen the largest possible unit of this measurement will be half an inch that is one by two inches. Similarly with four lines this represents the unit of four by sixteen inches that is equal to a quarter inch or one by four inches. Here let us consider an example. Here we are given a twelve inch ruler and we have to find the measurement indicated by this arrow. Let us see it closely. We already know that in an inch the longest line in the middle marks the half inch and there is only one such line in an inch and here between one and two this is the longest line. So this line is representing one by two inches but this is to the right of one inches that means it is representing one and a half inches. So the arrow indicates measurement of one and a half inches. Now we are going to discuss how to use metric rulers to measure length. Metric rulers are very easy to read because they deal with millimeters and centimeters only. Now this is a metric ruler. Now let us consider an example. Now here we are given a ten centimeter ruler and we have to find the measurement indicated by this arrow. Now here the smaller lines in the scale are millimeters and larger lines with numbers are centimeters. Here we have to see the difference between increment of millimeters and centimeters. You can see between two consecutive larger lines representing centimeters there are ten small divisions that is one centimeter is equal to ten millimeters or we can write one millimeter is equal to one by ten centimeter. It means if you measure two lines after one centimeter then it is one point two centimeters or we can also write it as twelve millimeters. Now here the arrow is given at the third line after four centimeters so it is four point three centimeters or forty three millimeters. Thus in this session we have discussed how to use US and metric rulers to measure length. This completes our session. Hope you enjoyed this session.