Euler_Problem-020.b93

v0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
v0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
>"d">1-:!#v_:03p013p"~I"+23p>23g"d"%1+23g"d"/g"0"-03g*13g+:55+%68 v
    ^     $#               _^#!p32:-1g32p31/+55p/"d"g32+1%"d"g32+*<
          >"~I"+33p0>33g"d"%1+33g"d"/g"0"-+  33g:1-33p v
                 @._^#!                                <


[0,3] current multiplicand
[1,3] carry
[2,3] multiplication index
[3,3] sum index


---------------------------------------

The approach is similar to problem 16 - the main task was implementing a long multiplication algorithm in Befunge. 
Then, after 100! is calculated we only need to sum the individual digits.