求未知数x：9x﹣1.8=5.4．
估算． 4.83×0.52≈ 5.03×3.98≈ 4.01×8.9≈ 15.2÷2.9≈ 4.83÷0.21≈ 55.8÷3.9≈
口算：0.3÷0.1= 3.25×4= 15.5+0.45= 23×0.02= 0+2÷4=302= 0.43= 3.05÷100= 1﹣0.99= 4.5÷3×3=
直接写得数 8.6+4= 0.35÷0.7= 6.5×0.2= 0.7×0.9= 7.2+2.8=0.96÷0.03= 12×2.5= 8.4÷4.2= 1.4×5= 1.68÷0.3=3.1×0.03= 27+456+73= 1÷0.25= 7.2×0.3= 0.99+1.8=1.2÷3= 2.3+1.9= 7.6÷4= 0.3×0.02= 2.87÷0.7=
直接写得数． 0.99+1.8= 1.5×0.4= 0÷4.86= 0.84÷2=2.5﹣0.05= 0.72÷0.9= 2.4÷0.06= 0.8×1.25=0.3×0.3= 10×0.07= 0.05×7= 0.2×0.26=
直接写出得数．5.43+1.07= 3.05×0.4= 0.46÷4.6= 3.7﹣2.9= 0.8×1.25=0.27÷3= 70÷0.5= 0.25×0.4= 1.7+0.43+3.3= 9.8﹣2.6﹣2.4=
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