We investigate what arithmetic would look like if carry digits into other
digit position were ignored, so that 9 + 4 = 3, 5 + 5 = 0, 9 X 4 = 6, 5 X 4 =
0, and so on. For example, the primes are now 21, 23, 25, 27, 29, 41, 43, 45,
47, ... .Comment: 7 pages. To the memory of Martin Gardner (October 21, 1914 -- May 22,
2010). Revised version (with a number of small improvements), July 7 201
