28×5+2×3×35+21×20+14×40+8×62 55×66+66×77+77×88+88×99
问题描述：
28×5+2×3×35+21×20+14×40+8×62 55×66+66×77+77×88+88×99
脱式计算
答
28×5+2×4×35+21×20+14×40+8×62 =2×2×7×5+2×4×5×7+3×7×4×5+2×7×5×2×4+8×62=2×2×7×5×（1+2+3+4）+496 =10×14×10+496 =1400+496 =1896 55×66+66×77+77×88+88×99=11×5×11×6+11×6×11...