用竖式计算下列各题。 (1)50-13-18 = (2) 35+24-16 = (3)27+15+21 = (4)28-14+30 =
10+20= 10+40= 10+50= 10+70= 20+20= 20+40= 20+50= 20+70=
30×1=____ 30×2=____ 30×3=____
20×1=____ 20×2=____ 20×3=____ 20×4=____
10×1=____ 10×2=____ 10×3=____ 10×4=____
41+7= 43+4= 47+7= 48+8= 81+7= 83+4= 87+7= 88+8=