口算下面各题 (1)2.5+3.2= (2)9.8-4.8= (3)1.29-0.18= (4)2.26+0.9= (5)8-0.82= (6)0.75+0.25= (7)1.4+0.5= (8)10.8-8.5= (9)6.4+1.07= (10)0.55+5.5= (11)1.05-0.09= (12)0.6+6.45=
2×15﹣(5+5) ×54(9+7)÷() 97×2000﹣96×2001.
5﹣2+= (12.5+)×8= 19﹣3﹣4= 8+0.1÷0.1﹣8=21﹣2.897= 0.25×0.12= 3.6÷25%×4= =
一个半圆面,半径是R,它的周长是 .
认真计算:2.5×3.2×12.5 48×31+31×51+31.
直接写出得数:4×=﹣=+0.25=÷×=﹣3﹣2=