用一副三角板画出15゜角、105゜角.
用小数计算. 5元6角﹣2元9角 3元4角+8元8角 8角+9角 7分﹣5分.
计算. 2.5+7.5= 9.8﹣0.8= 1.4+7.6= 4.5+5.5= 19.8﹣9.8= 9.4+0.6=
用竖式计算并验算. (1)2.47+3.24= (2)4.7﹣1.562= (3)100﹣27.5=
计算:0.1+0.3+0.5+0.7+0.9+0.1 1+0.13+0.15+0.17+0.19.
把下面的算式补充完整. 18.7﹣16.4+ =18.7+ ﹣l6.4 =20﹣16.4 = 35.67+ +21.35 =35.67+( +21.35) =35.67+50 = 54.37﹣ ﹣9.23 =54.37﹣( +9.23) =54.37﹣10 = 33.25+6.23﹣ =33.25﹣ +6.23 =30+6.23 = .