First of all cut of the top and the bottom of the cylinder to get two circles. Now take a scissors and cut of the cylinder into two halves from the top to the bottom as shown. Now you get a rectangle shape. You can easily measure the length of the cylinder but to measure the base is a problem. So mark a point on the table with tape and also make a mark on the can or the object you want to measure. Now place the two points over each other. Now use a ruler as a guide and move the can so that the mark makes one complete turn and touches the surface. Now mark this point with a tape. Now you have to measure the distance. The area formula for the two circles, A =2(pie)(square of radius). And to calculate the area of the rectangular portion of the cylinder= (base) x (length of perpendicular height). Base = circumference of the circle, C=2(pie)(radius). From here we get the area = 2(pie)(radius)(perpendicular eight). Now to find the total surface area of the rectangle you need to add the area of the two circles and the area of the rectangle. That's it.