Question

reconstruieste operatiile:
MMMM+
NNNN
OOOO
---------
MNNNO


RRRR x
RRR
---------
OOOO
OOOO
OOOO
----------
OMTRWO

Answer 1

MMMM+
  NNNN
 OOOO
MNNNO

Observam ca M+N=10
1+O=N
M=1 => N=8=>O=8 =>

  1111+
  9999
  8888
19998
_________________________________________________________________

       RRRR x
         RRR
      OOOO
   OOOO
OOOO
OMTRWO

Observam ca R² <10 => R∈{2,3}
Daca R=3  OMTRWO ar avea 7 cifre iar r=8≠3
=> R=2 => O=4 :
     2222 x
      222
    4444
  4444
4444
493284