ArrayFormCompute←{

     _U_←{⍵⍵⍣¯1⊢⍺ ⍺⍺⍥⍵⍵ ⍵}   ⍝ Under operator
     AFC←+_U_(10∘⊥)
⍝ Tests
     1 2 4 6≢12 AFC 1 2 3 4:∘∘∘
     4 5 5≢181 AFC 2 7 4:∘∘∘
     1 0 0 0≢1 AFC 9 9 9:∘∘∘
     1 9 9 9 9≢9999 AFC 1 0 0 0 0:∘∘∘
     1 0 0 0≢1000 AFC 0:∘∘∘

     'All tests passed.'

 }