7: 5.8×4=23.2 30÷5.8=5
8: 一班 ﹙107+113+121+109+120+104﹚÷6 =674÷6 =112
﹙98+105+92+96+121+124﹚÷6 =636÷6 =106
9: 164.5÷3.5=47 202.5÷4.5=45 47>45 上午 快
10: ⑴ 15.2×8.8=133.76 ≈133.8
⑵ 300÷﹙15.2+8.8﹚ =300÷24 =12.5
11: ⑴ 0.25×12×2=6 ⑵ 0.25×3÷2=0.375 0.23×3÷2=0.345 |