I have enjoyed books for as long as I can remember and have been enjoying myself today organizing all the books I have in my Kindle library into collections on my new Kindle Paperwhite. I have several Maths books on my Kindle, many of which were free. Now you don’t have to own a Kindle to read Kindle books as the Kindle app is free to download for any device you may own: PC, phone or tablet. It is possible to search Kindle books by price, so a search on Mathematics books by price from lowest to highest will give all the free entries (worth keeping an eye on as these can change) first. It is worth noting that currently 50 mathematical ideas you really need to know is available on Kindle for £1.54 UK $2.52 US.
Looking at the books currently on offer for free, these include some books from CK-12 (for more information on these see below), Mind Hurdles: Mystery Number – a set of ‘number mysteries’, one or more of which would make a good lesson starter and Henry Ernest Dudeney’s – Amusements in Mathematics a puzzle collection (with solutions). The first set of puzzles will offer a trip down memory lane for those who remember money – pre-decimal! There are several categories of puzzles available.
Having downloaded a CK-12 book I discovered another whole collection. CK-12 provides an extensive range of open-source content and technology tools for students and teachers. See for example the algebra resources here; click on FlexBooks to see the available books. Books such as CK-12 Algebra – second edition can be downloaded free in various formats, PDF, mobi and ePub. To download books you will need to sign in (free); you can create an account or sign in with Google, Facebook or Twitter. Looking at the Algebra books, this looks useful: Algebra Explorations for Pre-K through Grade 7 (so age 3 to 12)
There are many other free Maths books online as you will discover with a little searching, see these for example. A couple of free books I have mentioned before but I think are worth another mention:
The first is a complete GCSE text from Clear Creative Learning, don’t be put off by the 2007 date – this is still useful, note the link to download a free pdf. The text includes numerous set of questions for each topic by grade with solutions for all the examples.
The other is ‘Street Fighting Mathematics‘ by Sanjoy Mahajan, with the excellent sub-title ‘The Art of Educated Guessing and Opportunistic Problem Solving’ (note the link on the left to the free Creative Commons edition under Essential Info).
Any discussion on free Maths texts should include of course all the free texts available on the wonderful CIMT site (Centre for Innovation in Mathematics Teaching).
I wrote recently on the treasure trove that is the National STEM Centre; the resources here include books, the search function described in that post includes the facility to search by type and one of the options is textbook. This search for example is the result of searching for texts on equations.
You could even write your own! If publishing your own Kindle eBook feels a little too much right now – you could try something simpler!