add sub mul div modulo in assembly

.model small
.data
mes db  'Enter a number[000 - 999] ', '$'
input db 0
input2 db 0
.stack 100h
.code

getchar proc

mov ah, 01h
int 21h
ret

getchar endp

newline proc

mov dl, 10
mov ah, 02h
int 21h
ret
newline endp



    main    proc

mov ax, @data
mov ds, ax

lea dx, mes
mov ah, 09h
int 21h

call getchar

sub al, 48
mov bl, 100
mul bl

add input , al

call getchar

sub al, 48
mov bl, 10
mul bl


add input , al

call getchar

sub al, 48
mov bl, 1
mul bl

add input , al

call newline

lea dx, mes
mov ah, 09h
int 21h


call getchar

sub al, 48
mov bl, 100
mul bl

add input2 , al

call getchar

sub al, 48
mov bl, 10
mul bl


add input2 , al

call getchar

sub al, 48
mov bl, 1
mul bl

add input2 , al



mov ax, 4c00h
int 21h

main endp
end main