列式计算．（1）一个数减去319，差是488，这个数是多少？（2）一个数加上648得1000，这个数是多少？
直接写得数×4=6﹣=÷= 6÷1%=×0÷= 1÷=×= 10+×= 0.99×9+0.99=×5×7=
直接写得数． 10÷1%= 6.3×= 0×3.5= 4.2÷= 1.125×8=÷= 12﹣9.8= 3.6×2.5= 1.25××8=×2÷×2=
390×0.02=﹣= 5﹣1.4﹣1.6= 0.9﹣0.26= 81÷= 4×（0.6+1.9）= 0.23×400=×=﹣+= 0.9+99×0.9=
口算． 1.4×3=== 1.8+0.32== 36.1÷5.9≈ 298×31≈ 499+203≈
直接写出下面各题的结果． 28×2= 1.8+2.9= 4.8÷12= 10﹣0.9= 0.25×4=﹣=+=×= 1﹣75%=÷=
×4=6﹣
=
÷
= 6÷1%=
×0÷
= 1÷
=
×
= 10+
×
=
×5×7=
= 0×3.5= 4.2÷
=
÷
= 12﹣9.8= 3.6×2.5=
×8=
﹣
= 5﹣1.4﹣1.6= 0.9﹣0.26=
= 4×（0.6+1.9）= 0.23×400=
×
=
﹣
+
= 0.9+99×0.9=
=
= 1.8+0.32=
= 36.1÷5.9≈ 298×31≈ 499+203≈
﹣
=
+
=
×
=
÷
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