The pattern is to multiply by each time. The last operation is

The pattern in this series is to add , then subtract . The last operation is .

The pattern in this series is add , then divide by . The blank is then .

The pattern is to multiply by each time. The last operation is

The pattern for this series is multiply by , then add (Pay attention to the numbers after the blank! The first three are deceiving.) The operation to fill in the blank is:

The pattern for this series is multiply by , then add (Pay attention to the numbers after the blank! The first three are deceiving.) The operation to fill in the blank is:

The pattern in this series is add , then divide by . The blank is then .

The pattern in this series is to add , then subtract . The last operation is .

The pattern is divide by , then add . The operation before the blank is .

This series is comprised of two alternating patterns. The first is to add each time:

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The second is to divide by each time:

The blank belongs to the first pattern. The operation right before the blank is .