第5课时 小数加、减法的简算
5.93 +0.19+2.81 3.07－0.38－1.62
7.3＋2.7－7.3＋2.7 1.27+3.9+0.73+16.1
48.4＋2.78＋51.6－0.78
23.4－0.8－13.4－7.2
139.46—( 58.74+ 19.46 )
答案提示
5.93 +0.19+2.81 3.07－0.38－1.62
=5.93+(0.19+2.81) =3.07+(0.38+1.62)
=5.93+3 =3.07+2
=8.93 = 5.07
7.3＋2.7－7.3＋2.7 1.27+3.9+0.73+16.1
=7.3-7.3+2.7+2.7 =(1.27+0.73)+(3.9+16.1)
=0+2.7+2.7 =2+20
=5.4 =22
48.4＋2.78＋51.6－0.78 23.4－0.8－13.4－7.2
=(48.4+51.6)+(2.78-0.78) =(23.4-13.4)-(0.8+7.2)
=100-2 =10-8
=98 =2
139.46 — ( 58.74+ 19.46 )
=139.46-19.46-58.74
=120-58.74
=61.26