To calculate 25 percent of your grade, multiply your current grade by 0.25. For example, if your current grade is 85, then 25 percent of that grade is 85 × 0.25 = 21.25 points.
If you're trying to find what a specific assignment or test worth 25% of your final grade will contribute, multiply that assignment's score by 0.25. For instance, if an exam worth 25% of your final grade earns you 90 points out of 100, it contributes 90 × 0.25 = 22.5 points toward your final grade.
To find your weighted grade when assignments have different percentages, multiply each grade by its percentage weight (as a decimal), then add all the results together. Example: if participation is 20% and you scored 95, midterm is 25% and you scored 80, and final is 55% and you scored 88, your final grade would be (95 × 0.20) + (80 × 0.25) + (88 × 0.55) = 19 + 20 + 48.4 = 87.4.
The key is converting the percentage to a decimal by dividing by 100, then multiplying your score by that decimal. This calculation works whether you're finding a component of your grade or determining what you need to score on a 25%-weighted assignment to reach a target final grade.