Percentages reduce ratios to an amount per 100. Percentages help you to compare ratios of different sizes. Figuring the percentage remaining helps you put the work done so far in perspective. For example, if you have 50 miles left to travel to get to your destination, you could be very close if you've already traveled 950 miles, or you could just be getting started if your total trip is only 55 miles.

Subtract the amount completed from the total amount needed to be done to find the amount remaining. For example, if you want to raise $250 and you've raised $100, subtract $100 from $250 to find you need $150 more.

Divide the amount remaining by the total amount. In this example, divide $150 by $250 to get 0.6.

Multiply the result by 100 to find the remaining percentage. In this example, multiply 0.6 by 100 to find the percentage remaining equals 60 percent.