Identify the pattern in the circle
Check the sequence of numbers clockwise or counterclockwise
Find the common difference, ratio, or rule
Compare opposite positions if the circle is symmetrical
Look for sums of adjacent numbers if the pattern is additive
Look for multiplication or division if the pattern is geometric
Check for alternating patterns
Use the known numbers to test possible values
Verify the missing number fits all related positions
Fill in the number that completes the pattern