小学数学运算

4/12+4/20+4/30+...4/49*50


567+345*566/567*345+222

4/12+4/20+4/30+...4/49*50
=4*[(4-3)/(3*4)+(5-4)/(4*5)+...+(50-49)/(49*50)]
=4*[1/3-1/4+1/4-1/5+...+1/49-1/50]
=4*(1/3-1/50)
=4*(47/150)
=94/75

(567+345*566)/(567*345+222)....加上括号,表示分子(分母)一个整体.
=(567+345*567-345)/(567*345+567-345)...仔细观察各数之间关系.
=1