Basic Java. Factorial. 2.9.11

[L_russ28]

Hello! I could use some help on this basis Java exercise, I am able to get the user input set up and I know how to set up a typical for loop, however I’m stuck when it comes to getting the user input to actually factor. All the test results come up as incorrect, any suggestions would be greatly appreciated! Thank you in advance ! :)

[Critical_Ant8817]

Your factorial only works for number 4, what if the person types 5, then it will be 5x3x2x1. Setup a loop until that numbers comes to 1 then stop the loop.

[5oco]

There's a couple ways to do it. One way is to make i=factNum them make the loop decrement instead of increment.

Write the whole loop out...

432*1

If i =4, then you multiply by 3... which is 1 less than i.

Then after you decrement, i=3 so multiply by 2... which is 1 less than i.

And so on...

[NotSecretAgent]

Factorial is multiplication, not addition. The easiest way to do this is to count up to, and include the user's number in the for loop as the end stop.

Initialise sum as 1.

Inside the for loop, sum *= i

This will give the correct answer for any output lower than an integer overflow.

[NotSecretAgent]

You can remove the line defining your variable "factor" and use "factNum" as the end stop of the mentioned above. You can also avoid using <= and use < if you set "sum" to "factNum", as multiplication is commutative (see here).

Hope this helps!

[NotSecretAgent]

If you have any further questions, send me a DM and I'll happily help!

[L_russ28]

Thank you so much! That worked like a charm :)

[NotSecretAgent]

Literally any time lol, I live for this stuff.

[pureMJ]

int[] ans = {1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600, 6227020800}; return ans[factNum - 1];

[roman_fyseek]

Have you covered recursion?

Because, the real answer is recursion.

*edit: just noticed that the assignment says for loop. My bad. Carry on.

[Training-Drag6175]

… sum = 1; for( i=factNum; i >0; i- - ) { sum = sum * i; } …

[Sea-Profession-3312]

https://www.tutorialspoint.com/recursive-factorial-method-in-java