1、 1-2+3-4+5-6-7+8-9+10-11+12=0 -1+2-3+4-5+6+7-8+9-10+11-12=0 11个数中共有6个奇数,5个偶数.根据奇偶规律,能变成零 2、 3 × (4 - 6 + 10) 3 × ((4 - 6) + 10) 3 × (4 - (6 - 10)) 3 × (4 + 10 - 6) 3 × ((4 + 10) - 6) 3 × (4 + (10 - 6)) 3 × 6 - 4 + 10 (3 × 6) - 4 + 10 (3 × 6 - 4) + 10 ((3 × 6) - 4) + 10 (5 × 13 + 7) ÷ 3 ((5 × 13) + 7) ÷ 3 (7 + 5 × 13) ÷ 3 (7 + (5 × 13)) ÷ 3 (7 + 13 × 5) ÷ 3 (7 + (13 × 5)) ÷ 3 (13 × 5 + 7) ÷ 3 ((13 × 5) + 7) ÷ 3