Question

用递等式计算（能简算的要简算）

用递等式计算（能简算的要简算）：
①7.31+8.6+1.69+1.3 ②35.69+4.4-5.69 ③67.84-（11.58+27.84）④ 100.01-56.7-3.3 ⑤16.56-3.8+6.2 ⑥9.3+9.4+9.5+8.9+9.3
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Answer 1

①7.31+8.6+1.69+1.3
=（7.31+1.69）+8.6+1.3
=9+8.6+1.3
=17.6+1.3
=18.9

②35.69+4.4-5.69
=（35.69-5.69）+4.4
=30+4.4
=34.4

③67.84-（11.58+27.84）
=67.84-11.58-27.84
=（67.84-27.84)-11.58
=40-11.58
=28.42

④ 100.01-56.7-3.3
=100.01-(56.7+3.3)
=100.01-60
=40.01

⑤16.56-3.8+6.2
=16.56+6.2-3.8
=22.76-3.8
=18.96

⑥9.3+9.4+9.5+8.9+9.3
=9+0.3+9+0.4+9+0.5+9-0.1+9+0.3
=9x5+(0.3+0.4+0.5-0.1+0.3)
=45+1.4
=45.14