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2 egal 2+4+6+...+1080

Răspuns :

S=2+4+6+...+1080=2*(1+2+3+.....+540)=540*541/2 *2= 292140

1080:2=540
1+2+...540=
540x541:2x2=292140

sau

540x1082:2=
584280:2=292140