irb(main):001:0> def fact(n)
irb(main):002:1>   if (n <= 1)
irb(main):003:2>     1
irb(main):004:2>   else
irb(main):005:2*     n * fact(n - 1)
irb(main):006:2>   end
irb(main):007:1> end
=> nil
irb(main):008:0> fact(365)
=> 25104128675558732292929443748812027705165520269876079766872595193901106138220
93741966601800900025416937617231436098232866070807112336997985344536791065387238
35997043555327409376780914914294408643160469250745101348470255460140980059079655
41041195496105311886173373435145517193282760847755882291690213539123479186274701
51939680850494072260703300124632839880055048742799987669041697343786107818534466
79668715110496538881301368361990105291800561258445494886486176829158263475641489
90984138067809999604687488146734837340699359838791124995957584538873616661533093
25355125684505604638873812970295138115186141368892298651000544094394301469924411
25557552791407604927642537402504103910564219790032896000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000
irb(main):009:0>