nice

you dont even need loops, arithmetic progression sum is (a1+an)*n/2. I guess that exercise is about learning synthax. Otherwise i would be able to do it in straightforward formula in excel without loops.

Much more elegant than my solution.

I guess you should start with i=3, because 0, 1, 2 does not satisfy this condition

so easy with your solution !

wth!!!!

0 делится и на 3 и на 5.

It's not the best practice at all !!

Why is the for loop starting at 0 ?

Solution is concise but if thenumber is large, this code will not perform well.

It's definetely not the best practice.
At least why do you make int counter in loop =0 ?
0,1,2 never will be multiple to 3,5, you just add 3 redundant iterations
Just so much dissapointed to see that this solution marked as a good one

Not effective enough. You dont need to look at all numbers. This solution will have performance issues.

How about my code? im beginner

It may be a solution that comes in mind at first, but it is not the most efficient one. Please check overview at project euler solution to understand that i can be simplified to equation with O(1) memory complexity.

How come this is clever ... Lol