誰幫我出幾道簡便運算？五年級小數加減法馬上給我！好的話在給五分

34.5×8.23-34.5+2.77×34.519.98×37-199.8×1.9+1998×0.82314×0.043+3.14×7.2-31.4×0.153.9×1.2+0.1275×4.7+15.9×257.5×23+31×2.5答案：34.5×8.23-34.5+2.77×34.5=34.5*（8.23-1+2.77）=34.5*10=34519….