Area of Beijing: A ≈ 16400km2
Take standard marble diameter: d = 5/8"
Number of marbles of 1 marble depth required to cover Beijing: N ≈ A/d2 ≈ 6.5*1013
One mole of marbles = Avogadro's number worth of marbles; Av ≈ 6*1023
Depth of Avogadro's number of marbles on Beijing ≈ d*Av/N ≈ 1.5*105 km
They would reach about half way to the moon!
Area of Beijing: A ≈ 16400km2
Take standard marble diameter: d = 5/8"
Number of marbles of 1 marble depth required to cover Beijing: N ≈ A/d2 ≈ 6.5*1013
One mole of marbles = Avogadro's number worth of marbles; Av ≈ 6*1023
Depth of Avogadro's number of marbles on Beijing ≈ d*Av/N ≈ 1.5*105 km
They would reach about half way to the moon!