Which option gives the two numbers that should replace the question marks (?), in order, in the series below?
6, 11, 21, 36, ?, 81, ?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 56, 111
Look at the difference between each pair of terms. The differences are the multiples of 5 in order:
\(11-6=5\), \(21-11=10\), \(36-21=15\)
Next difference 20: \(36+20=56\)
Next difference 25: \(56+25=81\), which matches the given term
Next difference 30: \(81+30=111\)
So the missing numbers are 56 and 111.