Which mathematical constant has created a major annual retail event that drives significant sales increases for certain businesses?

Mathematics and retail have formed fascinating partnerships over the years, especially around mathematical constants and special dates. One particular mathematical constant has become a surprising retail success story, generating millions in sales for specific businesses that have creatively leveraged this number for marketing purposes. Test your knowledge about this intersection of mathematical culture and retail innovation!

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Pi (π) - celebrated on March 14 (3/14), driving sales for pizza chains, pie shops, and math-themed merchandise
Euler's number (e) - celebrated on February 71 (2.71), boosting sales for electronic retailers and engineering supply stores
The Golden Ratio (φ) - celebrated on January 62 (1.62), increasing sales for art supplies and design software
The Square Root of 2 (√2) - celebrated on January 41 (1.41), generating revenue for square-shaped products and geometry tools