43×28+23×28+66×39+33×66=(43+23)×28+66×(39+33)=66×28+66×72=66×(28+72)=66×100=6600
43×28+23×28+66×39+33×66=28×(43+23)+66×(39+33)=28×66+66×72=66×(28+72)=66×100=6600