估算:705500-50800≈5035433-205000≈305500-108900≈805433+205000≈855500-579900≈533533-205130≈
计算: (1)73× (2) 166÷41
计算:(1)×37(2)2004×
计算:
计算:(1998+19981998+199819981998+…)÷(1999+19991999+199919991999…)×1999