PROGRAM Fact_Ext_Func

IMPLICIT NONE

INTERFACE

FUNCTION Fact(K)

INTEGER :: Fact

INTEGER, INTENT(IN) :: K

END FUNCTION Fact

END INTERFACE

INTEGER :: N

PRINT *, “Enter a positive integer N”

READ *, N

PRINT *, N,”!= “, Fact(N)

END PROGRAM Fact_Ext_Func

FUNCTION FACT(K)

IMPLICIT NONE

INTEGER :: FACT, I

INTEGER, INTENT(IN) :: K

FACT=1

DO I=1, K

FACT=FACT*I

END DO

END FUNCTION FACT