RosettaCodeData/Task/Factorial/CMake/factorial.cmake

function(factorial var n)
  set(product 1)
  foreach(i RANGE 2 ${n})
    math(EXPR product "${product} * ${i}")
  endforeach(i)
  set(${var} ${product} PARENT_SCOPE)
endfunction(factorial)

factorial(f 12)
message("12! = ${f}")