Fortran 90 Source Code

! Author: Hannes du Plooy
! Date: 8 October 2013
! Objective: To solve the following
!  ONE
!  ONE
!  ONE
! +ONE
! ----
!  TEN

program puzzle001
    implicit none
    integer :: O, E, N, T, E2, carry1, tmp1, carry2, tmp2
    character(len=4) :: line

    do O=1,9
        do E=0,9
            if (O /= E) then
                tmp1 = E*4
                carry1 = tmp1 / 10
                N = MOD(tmp1,10)
                tmp2 = carry1 + N*4
                carry2 = tmp2 / 10
                E2 = MOD(tmp2,10)
                T = carry2 + O*4 
                if (N /= O .and. N /= E .and. E2 == E .and. T < 10 .and. T /= O .and. T /= E .and. T /= N) then
                    write(*,*) "Answer is"
                    write(*,*) ""
                    line = " " // char(O+48) // char(N+48) // char(E+48)
                    write(*,*) line
                    write(*,*) line
                    write(*,*) line
                    write(*,*) "+" // char(O+48) // char(N+48) // char(E+48)
                    write(*,*) "----"
                    write(*,*) " " // char(T+48) // char(E+48) // char(N+48)
                    stop                    
                endif    
            endif
        enddo
    enddo
end program