Assembly Program To Check Given Three-Digit Number Is Even Or Odd

readnum macro num
mov ah, 01h
int 21h
sub al, '0'
mov bh, 0ah
mul bh
mov num, al
mov ah, 01h
int 21h
sub al, '0'
add num, al
mov al, num
mov bh, 0ah
mul bh
mov num, al
mov ah, 01h
int 21h
sub al, '0'
add num, al

endm

printstring macro msg
mov ah, 09h
mov dx, offset msg
int 21h
endm

data segment
cr equ 0dh
lf equ 0ah
msg1 db 'Enter a three digit number','$'
msg2 db cr, lf, 'This is a even number','$'
msg3 db cr,lf, 'This is a odd number','$'

num db ?
data ends

code segment
assume cs:code, ds:data
start:
        mov ax, data
        mov ds, ax

        printstring msg1
        readnum num
        mov ah, 00
        mov al, num
        mov bl, 02
        div bl
        cmp ah, 00
        je evennum
        printstring msg3
        jmp skip

        evennum: 
                printstring msg2
        skip:
                mov ax, 4c00h
                int 21h
        code ends
        end start