How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
Consider all two digit numbers (10, 11, . . . ,99). In writing down all these numbers, which digits occur least often, and which occur most often ? What about three digit numbers, four digit numbers. . . .
How many six digit numbers are there which DO NOT contain a 5?
Dotty Six is a simple dice game that you can adapt in many ways.
Exploring the structure of a number square: how quickly can you put the number tiles in the right place on the grid?
Dotty Six game for an adult and child. Will you be the first to have three sixes in a straight line?
There are six numbers written in five different scripts. Can you sort out which is which?
This article explains how credit card numbers are defined and the check digit serves to verify their accuracy.
What are the last two digits of 2^(2^2003)?
These interactive dominoes can be dragged around the screen.
What is the last digit of the number 1 / 5^903 ?
A task which depends on members of the group noticing the needs of others and responding.