Canceling credit cards to raise fico score

So you've been told to cancel your credit cards to increase your scores :)
Hahah wrong...
Cancelling your credit cards will reduce your fico score because your account is aged and also has a credit line which contributes to your available total credit.
Let's say you've got 5 credit cards which each has a credit line of $500 dollars, now that's a total of $2500 dollars available to your total credit if there is no balance on them. Your current fico score is 650.

When you charge on them it will take away from your available credit, so spend $100 on 2 cards.
$100 * 2 = $200 - $2500 = $2300 total available credit.

When you close 3 of your cards now what happens,
$500 * 3 = $1500 closed

$2300 - $1500  = $800 total available credit.

Now your score just dropped from a 650 to a 578 ouch.
Don't start cancelling accounts that have aged and an available credit line that will only hurt your fico score not help it.