
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given that David's telephone numbers have the form $555-abc-defgh$, where $a$, $b$, $c$, $d$, $e$, $f$, $g$, $h$ are distinct digits and in increasing order, and none is either $0$ or $1$, calculate the total number of possible telephone numbers David can have.

Present the answer in LaTex format: \boxed{Your answer}
user