| d0=: [: >: #: | Add 1 to cyclic counter y with upper limit x | 
  | d1=: +//. | Sum items of y corresponding to keys x | 
| d2=: +//. {~ 'abcde'"_ i. ~.@[ | Sum y according to keys x from key set 'abcde'. (substitute your ordered keyset for 'abcde') | 
  | d3=: +. | Greatest common divisor of x and y | 
| m4=: >:@i.@(>./) |/ ] | 1 thru max y residues of y | 
| m5=: 0: = m4 | Locate positive integers <: y dividing y | 
| d6=: +"1 | Add x to each row of y | 
| d7=: + | Add list x to each column of table y | 
| d8=: + | Add list y to each column of table x | 
| d9=: *. | Least common multiple of x and y |