Copyright © University of Cambridge. All rights reserved.

'Phone Call' printed from https://nrich.maths.org/

Show menu


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.
You can find more short problems, arranged by curriculum topic, in our short problems collection.