
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 all of David's telephone numbers have the form $555-abc-defg$, where $a, b, c, d, e, f,$ and $g$ are distinct digits and in increasing order, and none is either $0$ or $1$, determine the number of different telephone numbers David can have.

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