Eastern rattlesnakes have 6 segments in their tails, while Western rattlesnakes have 8 segments. What is the percentage difference in their tail size, expressed as a percentage of the Western rattlesnake's tail size?
First find the difference in size between the two kinds of snake tail: 8 segments - 6 segments = 
<gadget id="calculator">8-6</gadget>
<output>2</output>
2 segments.
Then divide that amount by the size of the Western rattlesnake's tail and multiply by 100% to express the answer as a percentage: 2 segments / 8 segments * 100% = 25%

<result>25</result>