Step 1: Identify letters flipped along the vertical axis.
The letters flipped include:
\[
\text{p, q, b, d, m, w, n.}
\]
This gives a count of 7.
Step 2: Evaluate potential ambiguities.
Some interpretations may also consider \(6\) and \(y\) as flipped based on visual resemblance, which would add 2 more flipped letters.
Step 3: Conclude the possible answers.
The total flipped letters could be:
\[7 \text{ or } 9.\]