QA – Basics of Percentages

Percentages are a good way of comparing things. Percentages simply mean “per 100”.

So, if we say, ‘in future, 80% of engineers will be women’ it means that in the future, out of every 100 engineers, 80 will be women.

To convert a fraction into a per cent we have the following:

To convert any fraction to rate per cent, multiply it by 100 and put % sign, i.e.,

Similarly to convert a percentage into fraction, drop the per cent sign and divide the number by 100.

The given table can be used for quick calculations:

Fraction %age Fraction %age
1/2/2016 50% 1/9/2016 11.11%
1/3/2016 33.33% 1/10/2016 10%
1/4/2016 25% 1/11/2016 9.09%
1/5/2016 20% 1/12/2016 8.33%
1/6/2016 16.66% 1/13/2016 7.69%
1/7/2016 14.28% 1/14/2016 7.14%
1/8/2016 12.50% 1/15/2016 6.66%

To find the percentage change:

Percentage Change =[(Final Value – Initial Value) / Initial Value] x 100

Example: 2 employees were added in a company of 18 employees. So, how many employees would be added to a company of 100 employees?

The addition would be = (2 * 100) / 18 = 200/18 = 100/9 = 11.11

Additional Formulae for Percentages:

Successive Percentage:

Final value =  x(1 + (A/100)) (x + (b/100)) (1 + (c/100)) …….

If A x% more than that of B, then B is less than that of A by:

[ x/ (100 + x) * 100]%

If A is x% less than that of B, then B is more than that of A by :

[ x/ (100 – x) * 100]%

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