设有n个有理数x1,x2…xn.满足｜xi｜＜1（i=1,2…n）,且｜x1｜＋｜x2｜＋…＋｜xn｜＝19+｜x1＋x

若n≤19,
∵|xi|＜1(i=1,2,···,n)
∴|x1|+|x2|+······+|xn|＜n≤19≤19+|x1+x2+······+xn|,
与题中|x1|+|x2|+······+|xn|=19+|x1+x2+······+xn|矛盾!
考虑n=20,
令x1=x2=······=x10=-19/20,
x11=x12=······=x20=19/20,
则|x1|+|x2|+······+|xn|=19+|x1+x2+······+xn|,
满足题意,
∴n(min)=20.