Why don't percentages always add up to 100%?

Results are rounded to the nearest whole number and so, if you add up the percentage scores, sometimes this will mean that will not quite add up to 100%.

You may notice that sometimes a set of percentages don't always add up to exactly 100%. This is an expected result of rounding to the nearest whole number.

For example, three equal responses would give percentages of 33.3% each. When rounded to whole numbers we get 33%, 33% and 33% that together make only 99%.