Răspuns :

Alexs99id
2+4+6+...+2006 =
= 2(1+2+3+...+1003)
1+2+3+...+1003 (aflam cu suma lui Gauss : n(n+1)/2)
=1003(1003+1)/2

2 × (1003×1004)/2 = 1003 × 1004 = 1.007.012

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