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34.56-(4.56-3.7)= 6.6-2.91+3.4-1.09= 3.125+(6.875-1.72)-3.28

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34.56-(4.56-3.7)= 6.6-2.91+3.4-1.09= 3.125+(6.875-1.72)-3.28= 4.99+4.99+4.99+0.04+4.99= 巧算
34.56-(4.56-3.7)= 6.6-2.91+3.4-1.09= 3.125+(6.875-1.72)-3.28
34.56-(4.56-3.7)
=34.56-4.56+3.7
=33.7

6.6-2.91+3.4-1.09
=(6.6+3.4)-(2.91+1.09)
=10-4
=6

3.125+(6.875-1.72)-3.28
=(3.125+6.875)-(1.72+3.28)
=10-5
=5

4.99+4.99+4.99+0.04+4.99
=(5-0.01)×4+0.04
=5×4-0.01×4+0.04
=20-0.04+0.04
=20