Use a sharp knife or a pair of scissors to cut a small wedge out of the entire roll of tape from the outermost edge to the innermost end. This way, you'll tear the tape off in the same spot every time, and you may have less trouble finding the edge in the future! When you are done using a roll of tape for the time being, stick a toothpick underneath the adhesive about a half-inch from the edge. This way, when you return to use the tape again, you will be able to easily identify where to begin. This method is especially useful for clear packing tape. In theory, you can use almost anything to mark the end of the roll: paper, a paperclip, a twig, a card. Use anything that isn't too bulky and sticks cleanly to the edge of the tape. Improvise a solution using the materials you have lying around your home or office. Fold the sticky end of the tape back into the rollnot far, just a centimeter or soto make a "pull tab" for the next time you use the tape. You can fold the tape directly in, or you can fold at a 45-degree angle for a triangular fold. Consider buying a dedicated tape dispenser. These devices usually include a spool (which you can continually refill with new rolls of tape) and a serrated tape-cutting edge. When you stretch the tape over the serrated edge, it slices cleanly and naturally. The edge of the tape sticks there until you need it next. Consider buying a "tape gun" for packing tape. This device is a convenient, handheld version of the standard tape dispenser. Run the tape gun along the surface of a box, and you will seal the box without losing the edge of the roll. You can find tape dispensers online or at office-supply stores. Be aware that many standard tape dispensers are designed for use with Scotch tape It is easier to find the edge of a roll of patterned tape, as you can visually parse out the breaks in the pattern. If you consistently have trouble finding the edge of a roll of tape, consider making a habit of buying patterned tape for the sake of convenience. Some tape is designed with black lines on the sides to denote where the adhesive ends. This way, you will not need to find the edge of the roll you'll be able to pull it up at any point! Look for this specialty tape online or in large office-supply stores.
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One-sentence summary -- Cut a V-shape into the tape roll. Mark the end of the roll with a toothpick. Fold the edge of the tape back on itself. Use a tape dispenser. Buy striped or patterned tape. Buy sticky tape with non-stick sides.

You'll need to start by assembling a list of the numbers for which you'd like to find the weighted average. For example, if you're trying to find a weighted average for a series of grades in a class, first write down each of the grades. For instance, maybe your total grades are 82 for quizzes, 90 on your exam, and 76 on your term paper. Once you have your numbers, you'll need to know how much each of them weighs, or is worth, as part of your final average. For instance, in your class, the quizzes might be worth 20% of your total grade, while the exam is 35% and the term paper is 45%. In this case, the weights add up to 1 (or 100%). In order to use these percentages in your calculation, you'll need to convert them to decimal form. The resulting numbers are called "weighting factors." Once you have all your numbers, pair up each number (x) with its corresponding weighting factor (w). You'll be multiplying each set of numbers and weights together, then adding them all up to find the average. For example, if your total quiz score is 82 and quizzes are worth 20% of your grade, multiply 82 x 0.2. In this case, x=82 and w=0.2. The basic formula for a weighted average where the weights add up to 1 is x1(w1) + x2(w2) + x3(w3), and so on, where x is each number in your set and w is the corresponding weighting factor. To find your weighted average, simply multiply each number by its weight factor and then sum the resulting numbers up. For example: The weighted average for your quiz grades, exam, and term paper would be as follows: 82(0.2) + 90(0.35) + 76(0.45) = 16.4 + 31.5 + 34.2 = 82.1. This means you have a grade of 82.1% in the course.
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One-sentence summary --
Gather the numbers you would like to average. Determine the weight value of each number. Multiply each number by its weighting factor (w). Add the resulting numbers together to find the weighted average.