Question

Siind ca 3+6+9+…+abc=abc00;atunci a+b+c este egal cu?

Answer 1

3(1+2+3+........+n+abc/3) = 100·abc
1+2+3+.........+n+abc/3 = 100·abc/3
n(n+1)/2= 33·abc  n(n+1) = 66·abc = 198 ·abc/3       abc/3 = 199   abc = 579
a+b+c = 21
1+2+3+.......+199 = 199·200/2 = 19900
100·579/3 = 19900