Solve Carefully 230 – 220 x 0.5 = You probably won’t believe it but the answer is 5!
Social media users often find themselves drawn to maths-related brain teasers. Reason? It helps them to unwind and take a break from the stresses of daily life. What’s more, puzzle enthusiasts have to solve it solely from mental calculations without using a calculator or pen and paper….
.
.
.
.
.
.
Answer
230 – 220 x 0.5 =
230 – 110 =
120 =
The answer is 120?
Yes, but…
1 x 2 x 3 x 4 x 5 =
2 x 3 x 4 x 5 =
24 x 5 =
120 =
5 factorial = 5!
Multiplications must be done before subtractions (unless bracketing directs otherwise, which it does not here), so first we multiply 220 by 0.5, and half of 220 is 110, subtract that 110 from 230 to get 120, which is the same as 5 × 4 × 3 × 2 × 1, which is 5 factorial (the meaning of 5!—the exclamation point indicating the factorial operator and not excitement).
