1) Aflati x stiind ca (1+2+3+........+100):x = 101
(1+2+3+........+100):x =101
100(100+1)/2:x-101
50*101:x=101
50:x=1
x=50
2)Aflati 4 numere naturale consecutive stiind ca impartind suma lor la 5 obtinem catul 8 si restul 2
(a+a+1+a+2+a+3):5=8 si rest 2
(4a+6) :5= 8 si rest 2
4a+6=40+2
4a=42-6=36
a=9
a+1=10
a+2=11
a+3=12