I was recently at a local Plain bookstore where they sell lots of homeschool books. I found an orange, soft-covered book by Upton for each grade. It also had an identical book to go with it with all the answers written in! They were under 5 dollars each. The only reason I have not purchased it yet, is because there is little to no instruction. The Strayer Upton Practical Arithmetic books have, I think, a concise explanation of new topics throughout the book. I plan to go back to the store with my Strayer Upton book, and compare the table of contents in the S/U book, with the Upton workbook and see if one couldn't use the S/U textbook in tandem with this orange book. If that does not work out, I plan to print the free PDF of the Hamilton's Arithmetic books and have them spiral bound at my UPS store. I am weary of making copies of the Strayer Upton pages, and my children struggle with the small cramped spaces on such a little page. The Hamilton book looks as though the same person wrote it as the S/U books. We can always use S/U to further explanation if something isn't preferred.
PS I cannot find these Upton books on line anywhere. If anyone would like, I can follow up on this post with what I find out.