11.a) program iterate5^4 (iterate through all 4-digit numbers of a 5-based number system) for a from 0 to 5 step 1 for b from 0 to 5 step 1 for c from 0 to 5 step 1 for d from 0 to 5 step 1 output (a,b,c,d) next next next next end program iterate5^4 11.b) program iterate5^x (iterate through all x-digit numbers of a 5-based number system) parameters: x (integer), arr (array, optional) if x = 0 then output arr else for i from 0 to 5 step 1 iterate5^x (x-1, concatenate(arr, i)) next end if end program iterate5^x