# Escher Batman

Here is the process: I found the points of symmetry in Escher’s Lizard (No. 124), which has interesting rotational and reflectional symmetry. After a first failure, I discovered the importance of adding the lopsided grid formed by joining heads and tails – it keeps black and white “squares” from touching too much and presents lines that […]

# Base-seven Multiplication

I woke this morning thinking about base-seven numbers. Realizing that the standard base-ten multiplication process must work as well in base seven, I had to try it before getting out of bed. Base-seven numbers use powers of seven rather than powers of ten, so the digits turn over after 6. Counting in base seven goes […]