a + ( a + 2 ) + ( a + 4 ) + ( a + 6 ) + ( a + 8 ) + ( a + 10 ) + ( a + 12 ) = ?
a + a + 12 = 56
2 × a = 56 - 12
2 × a = 44
a = 44 : 2 ⇒ a = 22 → primul numar par
22 + 24 + 26 + 28 + 30 + 32 + 34 = 50 + 50 + 96 = 196 → suma celor sapte numere consecutive pare