Nowhere it says integer, it's always number (both in the title and the kata description)

As 8kyu, you can look up the solution to a challenge up to your level or one higher, so you'd be able to see up to 7kyu. This is to encourage users to practice kata at their level instead of jumping ahead. Ranking up in the earlier levels is quite fast, so I'd recommend doing some of the 7kyu katas if you feel like the 6kyu ones are too hard to figure out on your own initially, but you want to challenge yourself more than an 8kyu.