Happy Birthday To You Mystery Cache

A puzzle cache to celebrate my birthday. And yours. And to apologise for the trees.

To locate the cache simply follow these steps:

1. Take the date of your birthday (eg if your birthday is December 22nd, use "22")
2. Double it.
3. Add 9.
4. Subtract 3.
5. Divide by 2.
6. Subtract the date of your birthday.
7. Add four thousand seven hundred and thirty six.
8. Square it.
9. Square it again.
10. Subtract 140,598,519,815.

Add a spoonful of N's, W's, spaces, and dots, and check your working here.