一本数学书的体积约是300
北京到上海的铁路长约1460
12÷1000= 2- = 0.7n+0.4n= 3+3×=
+= 8÷= 8÷0.8×= ×2+=
1.56-0.6= 42-32= 2.5×13×4= (968+632)×0=
①3.72-+2.28-
②×14+
③36×()
④78×
⑤
⑥×[÷(+)]