1.计算:45.9÷[(82.4-36.5)×(3.5÷7)]=______.
2.计算:
=______.
3.计算:规定6*2=6+66=72;2*3=2+22+222=246;1*4=1+11+111+1111=1234,则7*5=______.
4.计算:2020.3-2019.2+2018.3-2017.2+…+4.3-3.2+2.3-1.2=______.
5.计算:0.258×447+0.258×678-0.258×125=______.
6.计算:12÷0.75÷0.8×(8×0.125-0.75)=______.
7.计算:0.1÷(0.2÷0.3)÷(0.3÷0.4)÷(0.4÷0.5)÷…÷(0.8÷0.9)=______.
8.计算:(14.76×0.78+1.02×14.76-0.8×14.76)÷7.38=______.
9.计算:2.019×201.7+20.18×20.16-201.8×2.017-20.19×20.16=______.
10.已知n 2 =123456.54321×(0.1+0.2+0.3+0.4+0.5+0.4+0.3+0.2+0.1),计算n=______.