NB. J Phrases Section 8D. Arithmetic

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