Which number will replace the question mark (?) in the following series?
2, 3, 10, 15, 26, 35, ?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 50
The terms lie close to the squares 1, 4, 9, 16, 25, 36. Each term is one more and one less than a square, alternately:
\(1^2+1=2\), \(2^2-1=3\)
\(3^2+1=10\), \(4^2-1=15\)
\(5^2+1=26\), \(6^2-1=35\)
The 7th term is \(7^2+1=49+1=50\)
So the missing number is 50.