I found these number blocks at http://www.learningresources.com/product/inflatable+number+blocks.do?search=basic&keyword=number+blocks&sortby=best&asc=true&page=1 they were on sale when I got ours. We fill up the laundry basket and Meara lays them out and matches the numbers together.
This is the description from Learning Resources: A fun and active way to learn your numbers! These clever inflatable blocks attached together with hook-and-loop fasteners to teach numerical order or build simple equations. Includes 26 blocks that feature numerals, Roman numerals, written names and domino-style dots for numbers 1 through 10. Math operation signs also included. Blocks are made of vinyl and deflate for storing.