Похоже принцип в том, чтобы вычитать из данного числа 9 до тех пор, пока оно не станет < 10, полученное число и будет ответом. Почему это работает, я тоже не понял.

Can someone explain this?

is it be more better if we use {for}?

What is happening here?
If the value from this class would return false, it would return true after changes?

NoSuchFieldException usually happens when you're using a different Java version than the code. If you use Java 8, it should work.

Can anyone explain how this works? I'm so confused. This doesn't even seem to be able to pass my IDE's compilition... Keeps getting NoSuchFieldException: modifiers.

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!)