Răspuns:
abcd+
bcd
cd
d
------------
1766
se observa ca d=4
1766-4d=1766-4·4=1750
se observa ca c=5
1750 -3·(5·10)=1750-150=1600
↓
c
se observa ca b=3
1600-2·(3·100)=1600-600=1000
↓
b
a=1
verificare:
abcd =1354
bcd = 354
cd = 54
d = 4
-----------------------
1766
