Identify the Odd One Out:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 273
A number is prime if no prime up to its square root divides it.
Option (1) 191 — \(13^2=169\lt191\lt196=14^2\), and none of 2, 3, 5, 7, 11, 13 divides 191, so it is a prime number.
Option (2) 149 — \(12^2=144\lt149\lt169\), and none of 2, 3, 5, 7, 11 divides 149, so it is a prime number.
Option (3) 273 — its digits add up to 12, so it is divisible by 3: \(273=3\times7\times13\). It is a composite number, so 273 is the odd one out among three primes.
Option (4) 233 — \(15^2=225\lt233\lt256=16^2\), and none of 2, 3, 5, 7, 11, 13 divides 233, so it is a prime number.