Dispropotionate presence of any unwanted substance which is harmful for human life is refered to as enviromental pollution.

Knowing how to calculate percentages will help you not only score well on a math test but in the real world as well. They are used for calculating tips in restaurants, finding out the nutritional content of your food, or even determining statistics of your favorite sports team. Regardless of how you plan to use the knowledge, calculating percentages is fundamental and quite easy overall.

isualize what a percentage represents. A percentage is an expression of part of the whole. Nothing is represented by 0%, and the whole amount is 100%. Everything else is somewhere in between![1]

For example, say you have 10 apples. If you eat 2 apples, then you have eaten 2 out of the whole 10 apples (2 / 10 × 100% = 20% eaten). If 10 apples is 100% and you ate 20%, then 100% - 20% = 80% of the apples remain.

The term "percent" in English comes from the Latin per centum, meaning “through 100” or “for 100”.

The percentage symbol is merely a format. In statistics, percentages are often left in their base form of 0 - 1, where 1 represents the whole. We merely multiply a decimal by a factor of 100% to format the answer.

**Determine the value of the whole.** In some cases, you will be given the value for part of the whole and the whole. Other times, you might get two parts that make up the whole. It is important to distinguish what the percentage is “of.” For instance, let's say we have a jar containing 1199 red marbles and 485 blue marbles, making it 1684 marbles in total. In this case, 1684 makes up a whole jar of marbles, i.e. 100%.^{[2]}