Question

四年级奥数题

3.89+3.87+3.83+3.85+3.84+3.86+3.88

Answer 1

3.89+3.87+3.83+3.85+3.84+3.86+3.88
=3.83+3.84+2.85+3.86+3.87+3.88+3.89
=3.86×7
=（4-0.14）×7
=28-0.98
=27.02

Answer 2

3.89+3.87+3.83+3.85+3.84+3.86+3.88
=3.8×7+（0.09+0.07+0.03+0.05+0.04+0.06+0.08）
=26.6+0.42
=27.02

不懂可追问，有帮助请采纳，谢谢！

Answer 3

3.89+3.87+3.83+3.85+3.84+3.86+3.88 (把每个数都看成是3.9)

=3.9×7－（0.01＋0.03＋0.07＋0.05＋0.06＋0.04＋0.02）
=27.3－0.28
=27.02

Answer 4

这是连续的数=3.86*7=27.02

Answer 5

=3*7+0.8*7+（0.07+0.03）+（0.04+0.06）+0.05+0.08+0.09
=21+5.6+0.1+0.1+0.22
=27.02