Why 5 stones?

David killed Goliath with 5 stones and a sling.

But why did David pick 5 stones where there was only one giant?
He has no faith? Thinking that if he missed one, he still have four more chances??

If you read the story further in 2Samuel, you will realised that Goliath had 4 sons.
That means, there were 5 giants! Which means to say, David wanted to kill the 5 giants all at one shot!

He has faith. Great faith! And his faith is specific. 5 giants, 5 stones.

He didnt go by the natural, bring 5 stones to kill 1 giant - flawed faith.
He didnt presume that he could kill more than 5 giants - presumptuous faith.
He has faith. And his faith is specific.

Dont be frustrated when you see the problems. Take one giant at a time.