There are 10 books on the table. Two-fifths of them are reading books and three-tenths of them are math books. There is one fewer science book than math books and the rest are history books. How many history books are there? Let's think first. Chain of thought:
Out of the 10 books, 10 x 2 / 5 = 4 are reading books. While 10 x 3 / 10 = 3 are math books. There are 3 - 1 = 2 science books. So, the total number of reading, math, and science books is 4 + 3 + 2 = 9. Thus, there is only 10 - 9 = 1 history book.
Therefore, the answer is 1.