It’s the end of the month again — time flies fast indeed. I’m on my way to a 1-week vacation, but before I leave for the airport, let us take a look at the posts for this month.

**Month in Review – April 2013**

- The Closure Property of Positive Real Numbers Under Addition
- Proving the Perpendicular Bisector Theorem Using SAS Congruence
- Proving The Perpendicular Bisector Theorem by Reflection
- The Reflection Postulate
- Linking Triangle Angle Sum and Inscribed Angle Theorems
- The Properties of Reflection
- Proof that -(a + b) = (-a) + (-b)
- Proof that (-a)(-b) = ab
- The Product of Negative Number and a Positive Number is Negative
- Proof that the Product of Any Number and Zero is Zero
- The Proof of the Cancellation Law of Addition

**Explore Proofs from the Book**

- To explore posts by month, visit the Post List page.
- To explore posts by category, visit the Categories page.
- To explore the all-time top posts, click the Top Posts page.

**Follow and Subscribe**

- Subscribe to PFTB’s RSS Feeds
- Receive PFTB’s email updates.
- Follow PFTB on Twitter at @proofsftb