wow!i have never heard of this package,which java version do you use?

What's the principle of this solution?

call contains in a while loop,it's a worst practices

wtf

I think the solution is clear and just need improve naming,don't know why someone always complain solution like this has poor readability,the code is not that long,any skilled programmer should understand its meaning just by it's function name in seconds,i rather hate long code that has bad format,a simple task should use short code to improve readability

(1 / n!) * (1! + 2! + 3! + ... + n!)
= (1 / n!) * n!+(1 / n!) * (n-1)!+(1 / n!) * (n-2)!+.....+(1 / n!) * 1
= (n!/n!)+((n-1)!/n!)+((n-2)!/n!)+.......+(1/n!)
= 1+(1/n)+(1/(n*(n-1)))+......+(1/n!)