Find the missing number from the given alternatives.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 99
Read the numbers in the six points of the star clockwise from the top: 9, 15, 27, 51, ?, 195. Each number is twice the one before it, minus 3.
\(9\times2-3=15\)
\(15\times2-3=27\)
\(27\times2-3=51\)
\(51\times2-3=99\), the missing number
\(99\times2-3=195\), the last number, so the rule holds all the way round
Tip: The differences 6, 12, 24, 48 double each time, which gives the same answer: \(51+48=99\) and \(99+96=195\).