# 50-Cent Piece Math Problem Stumps Students, Solution Shared Online

One specific math problem about a 50-cent piece recently went viral online after apparently stumping a lot of people.

BT reports that the multiple-choice math problem was used on an exam in Australia, which was taken by 17 and 18-year-old high school students.

The problem focuses on an illustration of two 50-cent piece coins positioned next to one another, joined together by one edge. According to the directions, students were asked to find the value of the degree of angle marked between the two coins in the picture since each coin had 12 edges of equal length.

Students were reportedly asked to choose one of the following five possible answers: 12, 30, 36, 60, or 72.

BT shared the responses of two students that found this particular math problem to be extremely difficult.

One student believed that it must have been an unfair trick question, claiming that “no one could have prepared for that.” However, another student simply argued that they were not given enough information about the coins in the first place to come up with the correct answer.

“The 50 cent coin question makes no sense to me as it asked us to find the angle, but it gave us no other angles or lengths to enter in the formulas so there was simply no way about it.”

On the other hand, quite a few people — including students and faculty members — apparently believed that the math problem was very easy to solve.

A substantial number of people have even mocked the individuals who struggled with the problem via social media.

According to the Daily Mail, the answer to this stumping math problem about a 50-cent piece is Option D — 60 degrees. How?

There are two different routes that can be taken which both lead to the same solution.

Focus on the Interior Angles

Within each shape, there are 12 interior angles. Subtracting 360 degrees from the product of the number of angles and 180 shows that the total sum is 1,800 degrees, which means that each individual angle is 150 degrees. With an interior angle of 150 degrees, the exterior angle has to be 30 degrees in order to complete a straight line measurement of 180 degrees. Two exterior angles meet at the marked angle in the problem, so multiplying 30 degrees by two equals 60 degrees.

Focus on the Exterior Angles

A simpler approach requires one to remember that the exterior angles of any shape will always equal 360 degrees. Dividing that number by 12 edges equals 30 degrees. Remembering that two exterior angles meet at the marked angle leads to the same final step of multiplication — 30 degrees times two angles equals 60 degrees.

Focus on a Triangle

According to the Daily Mail, there were also some students who paid attention to a completely different shape to solve this problem: the equilateral triangle. If you believe that the marked angle is part of an equilateral triangle, each angle within that three-angle shape is 60 degrees (for a grand total of 180 degrees).

This 50-cent piece math problem was originally designed for a high school exam in Australia. However, thanks to a screenshot and the viral buzz of the internet, it has apparently confused and upset people of all ages around the world.

[Image via Dollar Photo Club]