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Phone Call

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

A new taxi firm needs a memorable phone number. They want a number which has a maximum of two different digits. Their phone number must start with the digit $3$ and be six digits long. How many such numbers are possible?


If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.

This problem is taken from the UKMT Mathematical Challenges.
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