How many different ways can I lay 10 paving slabs, each 2 foot by 1
foot, to make a path 2 foot wide and 10 foot long from my back door
into my garden, without cutting any of the paving slabs?
Even Up
Age 11 to 14 Short Challenge Level
Consider all of the five-digit numbers which we can form using only
the digits 2, 4, 6 and 8.
If these numbers are arranged in ascending order, what is the 512th
number?