Hoặc
Ta có 120×999+1202×4×0,8×5×2,5×125=120×999+10,8×125×4×2,5×2×5
=120×1000100×10×10=12×10×10001000×10=12.
Vậy 120×999+1202×4×0,8×5×2,5×125=12 .