Question

Find the missing number (?) in the circle puzzle shown. 

• A. 18
• B. 11
• C. 8
• D. 7

Hint:

In circular number puzzles, compare the two outers flanking an inner cell—often their sum, product, or \textbf{difference} links to the inner via a square or cube.

Answer 1

The Correct Option is C

Observation: Each inner sector number has two adjacent outer numbers. The \emph{difference} between those two adjacent outer numbers equals the \emph{square} of the inner number.
[2pt] Check with known sectors:
For inner \(4\): outer numbers are \(4\) and \(20\). Difference \(=20-4=16=4^2\).
For inner \(5\): outer numbers are \(45\) and \(20\). Difference \(=45-20=25=5^2\).
For inner \(10\): outer numbers are \(120\) and \(20\). Difference \(=120-20=100=10^2\).
Thus, for the missing inner number \((?)\), the adjacent outer numbers are \(90\) and \(26\). Their difference is \(90-26=64=8^2\).
\(\Rightarrow\) The missing inner number is \(8\).
\(\boxed{8}\)