A4纸的长是29.7厘米、宽是21厘米,厚度是0.088毫米,换算成米,长=0.297米、宽=0.21米一包纸的质量:0.297×0.21×500×70=0.06237×500×70=2182.95(g)密度=质量÷体积2182.95÷(29.7×21×0.088÷10×500)=2182.95÷(5.48856×500)=2182.95÷2744.28=0.79545455(克/厘米³)A4纸的密度是0.79545455克/厘米³