五年級簡便運算快1/2+1/6+1/12+1/20+1/30+1/42+1/7=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)+1/7=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7=1恩，目前就做了這一個。2，五年級數學題簡算（0.75*42.7+57.3-0.573*25）/3*7972=(0.75*42.7+57.3*1-57.3*0.25)/3*7972=[0.75*42.7+57.3(1-...