Răspuns:
Explicație pas cu pas:
Evident, abc este par.
2+4+6+...+abc=abc·100. Vom transforma partea stanga a egalitatii
2+4+6+...+abc=2·(1+2+3+...+abc/2)=
[tex]=2*\frac{abc}{2}*(\frac{abc}{2}+1):2=\frac{abc}{2}*(\frac{abc}{2}+1) =abc*\frac{abc+2}{4}~~deci~ abc*\frac{abc+2}{4}=abc*100,~deci~ \frac{abc+2}{4}=100\\[/tex]
⇒abc+2=400, ⇒abc=398
