北师大版四年级下册《手拉手》ppt课件.ppt
手拉手,北师大版四年级数学下册,填空,5.9×2.5×0.4= 5.9 ×( 2.5 × 0.4 ) 7.8×0.15+2.2×0.15=( 7.8 + 2.2) × 0.15 0.2×1.25×5×8=( 0.2 × 5 )×( 1.25 × 8 ) 0.63×99+0.63=( 99 + 1 )×( 0.63 ),计算,能简算的要简算。,(1)2.6+1.4× 3 (2) 2.5× 0.6-1.8× 0.5 (3)(8+0.8)× 1.25 (4) 2.5× 2.8× 4 (5) 0.89×4.8+0.89×5.2 (6) 0.25× 32×1.25,(1)2.6+1.4× 3 =2.6+4.2 =6.8,解答,(2) 2.5× 0.6-1.8× 0.5 =1.5-0.9 = 0.6 2.5× 0.6-1.8× 0.5 =2.5× 0.6-(1.8÷3)×( 0.5 ×3) =2.5 ×0.6-0.6 ×1.5 =(2.5-1.5) ×0.6 =1 ×0.6 =0.6,(3)(8+0.8)× 1.25 =8× 1.25 + 0.8 × 1.25 =10+1 =11,(4) 2.5× 2.8× 4 =(2.5 × 4) × 2.8 =10 × 2.8 =28,(5) 0.89×4.8+0.89×5.2 =0.89×(4.8+5.2) =0.89 ×10 =8.9,(6)0.25× 32×1.25 =0.25 ×(4 × 8)×1.25 = ( 0.25 ×4 ) ×( 8×1.25) =1 ×10 =10,解决生活问题,一件雨衣售价30.80元,一双雨鞋售价19.20元,一把雨伞售价25元。张叔叔要买这样的4套雨具,带300元钱,够吗? (30.80+19.20+25)×4 =(50+25) ×4 =50 ×4+25 ×4 =200+100 =300(元) 300元=300元,下表是张老师家水、电的交费单,算一算各交多少钱?,水电费共需多少钱?,(1)用水多少立方米? 142.5130=12.5(立方米) (2)水费多少钱? 12.5×1.6 =12.5×(8×0.2) =12.5×8×0.2 =100×0.2 =20(元),(3)用电多少千瓦时? 210185=25(立方米) (4)电费多少钱? 0.44×25 =(0.44÷4)×(4×25) =0.11×100 =11(元) (5)水电费共需多少钱? 11+20=31(元) 答:水电费共需31元钱?,本节课我们主要学习了小数的一些运算,同学们要知道整数的一些运算定律,对小数同样适用,同学们要对比整数的计算方法,求解小数计算题。,本课小结,