问题标题:
计算:(1)0.1+0.2+0.3+0.4+…+0.9+0.1+0.11+0.12+…+0.98+0.99(2)121+12+13(1+12)×(1+13)+…+19(1+12)×(1+13)×…×(1+19).
问题描述:
计算:
(1)0.1+0.2+0.3+0.4+…+0.9+0.1+0.11+0.12+…+0.98+0.99
(2)
沙崇漠回答:
(1)0.1+0.2+0.3+0.4+…+0.9+0.1+0.11+0.12+…+0.98+0.99
=(0.1+0.9)×9÷2+(0.1+0.99)×90÷2
=4.5+49.05
=53.55
(2)121+12+13(1+12)×(1+13)
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