巧算1.1+1.2+1.3+1.4+…+9.7+9.8+9.9

2025-06-26 13:36:33
推荐回答(1个)
回答1:

1.1+1.2+1.3+1.4+…+9.7+9.8+9.9
=(1.1+9.9)+(1.2+9.8)+…+(5.4+5.6)+5.5
=11x5.4+5.5
=59.4+5.5=64.9