Add a number each time
Find the missing number in patterns that add the same number each time
Subtract a number each time
Pick the next term when subtracting the same number each time
Doubling each time
Pick the next number in these number doubling patterns
Halving each time
Pick the next number in these halving patterns
Fraction patterns
Choose the next number in each list of fractions
Square numbers
Pick the next number in these patterns of square numbers