用-2,4,5,7怎样算成24

(5+7)*(4-2)

=12*2

=24

负数可以看成为是正数,因为一个数+负数=-负数;-负数=+负数;*负数=/负数;/负数=*负数.
所以在此我就告诉你2，4，5，7的算法：
1: (4 - 2) × (5 + 7)
2: 4 ÷ 2 ×(5 + 7)
3: (4 ÷ 2) × (5 + 7)
4: 4 ÷ (2 ÷ (5 + 7))
5: (4 - 2) × (7 + 5)
6: 4 ÷ 2 ×(7 + 5)
7: (4 ÷ 2) × (7 + 5)
8: 4 ÷ (2 ÷ (7 + 5))
9: (4 × (5 + 7)) ÷ 2
10: 4 × (5 + 7) ÷ 2
11: 4 × ((5 + 7) ÷ 2)
12: (4 × (7 + 5)) ÷ 2
13: 4 × (7 + 5) ÷ 2
14: 4 × ((7 + 5) ÷ 2)
15: (5 + 7) ÷ 2 × 4
16: ((5 + 7) ÷ 2) × 4
17: (5 + 7) ÷ (2 ÷ 4)
18: (5 + 7) × (4 - 2)
19: (5 + 7) × 4 ÷ 2
20: ((5 + 7) × 4) ÷ 2
21: (5 + 7) × (4 ÷ 2)
22: (7 + 5) ÷ 2 × 4
23: ((7 + 5) ÷ 2) × 4
24: (7 + 5) ÷ (2 ÷ 4)
25: (7 + 5) × (4 - 2)
26: (7 + 5) × 4 ÷ 2
27: ((7 + 5) × 4) ÷ 2
28: (7 + 5) × (4 ÷ 2)

同意fcpc的意见。24点游戏可以锻炼人们对数的感觉，可以利用扑克牌玩这种游戏。设黑牌为正，红牌为负。经常进行这种游戏可提高计算能力和反应能力。祝你进步！

你可真是烂动脑 。。。 是 懒

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