Autumn was constantly misplacing her pencils. At the start of the school year, she purchased a pack of 20 pencils. In the first month of school, she misplaced 7 pencils, broke 3 pencils and had to throw them away, she found 4, and bought 2. How many pencils did Autumn have left? Let's think first. Chain of thought:
Autumn misplaced 7 and broke 3, so that lost her 7 + 3 = 10 pencils. Autumn found 4 pencils and bought 2, so she gained 4 + 2 = 6 pencils. She started with 20 pencils, lost 10 and gained 6 so she had 20 - 10 + 6 = 16 pencils left.
Therefore, the answer is 16.