3 : SUM.OF.N.A ( N -- SUM[N] , calculate sum of N integers )
4 0 \ starting value of SUM
6 OVER 0> \ Is N greater than zero?
9 SWAP 1- SWAP \ decrement N
11 SWAP DROP \ get rid on N
14 : SUM.OF.N.B ( N -- SUM[N] )
15 0 SWAP \ starting value of SUM
16 1+ 0 \ set indices for DO LOOP
17 ?DO \ safer than DO if N=0
22 : SUM.OF.N.C ( N -- SUM[N] )
23 0 \ starting value of SUM
32 : SUM.OF.N.D ( N -- SUM[N] )
33 >R \ put NUM on return stack
34 0 \ starting value of SUM
40 RDROP \ get rid of NUM
43 : SUM.OF.N.E { NUM | SUM -- SUM[N] , use return stack }
45 NUM +-> SUM \ add NUM to SUM
46 -1 +-> NUM \ decrement NUM
52 : SUM.OF.N.F ( NUM -- SUM[N] , Gauss' method )