Needle sizes

I’m knitting a slouchy hat for my friend and the pattern calls for size 13 us needles. Is there a way to make it in size 10 needles? Here’s a link to the pattern:http://www.ehow.com/how_12001444_make-knitted-slouchy-hat.html
Thanks!

Each stitch will be smaller, so you’ll need to cast on more stitches, in multiples of 4. The pattern doesn’t give measurements or gauge to go by, so it’s hard to say how many more you’d need to increase.

If you check out www.ravelry.com or www.knittingpatterncentral.com , you may be able to find a similar style hat that uses smaller needles than 13.

Here’s 4 pages of them done in a size 10 needle!
http://www.ravelry.com/patterns/search#craft=knitting&query=slouchy%20hat&sort=best&needles=6.0mm&view=captioned_thumbs

So, if I added, say, sixteen stitches to the original cast on, would that affect the amount of increases and decreases?

For the increases at the bottom to make it slouch you just do them as it says and it should work out fine since the cast will still bel a multiple of 4.