You say tiles but, judging by the size, I'm assuming you mean paving slabs. It's a while now since I laid any but please bear in mind that the size you are looking to buy are very heavy (approx twice the weight of 45cm square slabs), are more difficult to level and are much more prone to breaking when you bed them in and when you're cutting them to size. Consider using the smaller size and buy 30 (5 slabs x 6).
To make the mats easy just drawit on squared paper.
To cover the 222cm length you need 4 tiles (of which you'll use 3 whole ones and most of the other).
To cover the width you'll need 5 tiles (of which you'll use 4 whole and close to half of another.
So that's 20 in total.
That should give you room to play around a bit - for example if you want to put the part tiles all the way round the edge.
Yes, you could manage with a few less if you are prepared to have bits of tiles all over the place but 20 would look best.