Cockpitweb's software has the shapes and numbers on it-but not combined with the deviation indicator.
Its a test of capacity reduction whilst multi-tasking, and you'd be suprised how tricky this is when you actually try it. If you learn all the possible number sequences by heart this makes it all so much easier.
For e.g. if the difference between the numbers is 5, then the last digits in the countdown will have to be 9-4 or 8-3 or 7-2 or 6-1 or 5-0. These are the only possibilities. Similar sequences exist for differences of 2,3,4 etc. and there are not too many to learn them all!