Simple math challenges for middle schoolers are among the most viral content on the web. An image showing a calculation written in the palm of a hand is currently all the rage on Facebook. The promise is provocative: “Finish this if you’re a genius. 2 – 2 × 3 + 3. 95% failure rate . “
Mathematics
See more
Socks
E-mail
Philosophy
Upon reading this ultra-short text, the immediate reaction of most internet users is to respond within seconds. Yet, the comment sections are torn apart by completely different responses: 3 , -7 , 1 , or even -1 . Why does such a simple equation provoke so much disagreement?
WHY ARE 95% OF PEOPLE WRONG?
The error doesn’t stem from a lack of logic, but from forgetting the order of operations (the well-known rule known as PEMDAS or BODMAS ). Our brains naturally tend to read from left to right, which leads to two very common pitfalls:
The trap of reading directly (from left to right):
Some first calculate $2 – 2 = 0$ , then multiply by $3$ ( $0 \times 3 = 0$ ), and finally add $3$ . They thus find 3 .
The trap of poorly implemented PEMDAS:
Others remember that addition comes before subtraction in the word PEMDAS and do $3 + 3 = 6$ at the end, getting $2 – 6 = -4$ or other erroneous variations like $2 – (6 + 3) = -7$ .
Mathematics
THE STEP-BY-STEP SOLUTION: THE ABSOLUTE RULE
Multiplication takes precedence over addition and subtraction. Furthermore, addition and subtraction have the same priority and are performed simply from left to right.
Here is the exact sequence of events:
Priority to multiplication:
$$2 \times 3 = 6$$
The expression then becomes: $2 – 6 + 3$
Read more by clicking the (NEXT »») button below!
