1
3 ×3.14×(12.56÷3.14÷2) 2×3×1.45,
=3.14×4×1.45,
=12.56×1.45,
=18.212(吨);
18.212÷4≈5(次);
答:这堆黄沙约重18.212吨,需5次可以运完.