This bundle includes Subtraction Facts Book 1 and 2. Book 1 includes subtraction problems with minuends up to 18. Each page focuses on one minuend and is split into two columns; column one has all problems using that minuend in order, and column two has the same problems in a random order. Book 2 has a similar format, but with more randomization to increase the difficulty. The first 16 pages each focus on one minuend at a time, with problems in random order. The final 3 pages have more randomiza