계산: 11 × 4 + 14 × 7 + 17 × 10 +...+ 12005 × 2008.

계산: 11 × 4 + 14 × 7 + 17 × 10 +...+ 12005 × 2008.

11 × 4 + 14 × 7 + 17 x 10 +...+ 12005 × 2008 = 13 (1 - 14) + 13 (14 - 17) + 13 (17 - 110) +...+ 13 (12005 - 1800) = 13 (1 - 12008) = 6692008.