口算. 120÷6= 2000÷4= 3000÷5= 300÷3= 121×3= 505÷5= 960÷3= 69÷3= 78÷4≈ 249÷5≈ 83×9≈ 71×8≈
(66-32×1.2)÷0.25 12.5×(1618-8.4÷0.12)
(7.2-3.15)÷0.6×1.3 96.5×43.5+43.5×28.5-25×43.5
8.1×1.3-8×1.3+1.9×1.3+11.9÷1.36 [(7.6-5.2)÷0.4+2.54]×32
2.9×1.4+2×1.6 (2.44-1.8)÷0.4×20
18.5-(5.2+3.3)÷1.7 (2.5×8)÷(0.1-0.09)