竖式计算:315×3= 375×4=
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=