Many famous mathematical problems involve a particular kind of prime number, known as a Mersenne Number. In 1903, Dr. Frank Cole solved one of the most famous of these problems; almost 120 years after its delivery, his paper continues to charm both professional and armchair mathematicians. Dr. Cole presented a talk entitled, “On the Factoring of Large Numbers,” and wrote the following- and only the following!- on a chalkboard in answer to one of his generation’s greatest mathematical quandaries:

2^67 -1 = 193,707,721 × 761,838,257,287

The Mersenne pullover has Cole’s cheeky simplicity, with a firm commitment to figure flattering, office appropriate warmth. Lace detailing keeps things interesting, while the foundations of ribbing and stockinette give Mersenne the same earnest usefulness as simple mathematics. A softer silhouette fits best with about two inches of ease, to allow for easy layering and comfortable blackboard writing. Long sleeves are perfect for chilly classrooms and a casually rolled collar takes Mersenne easily from office lunch to dinner date.

Gauge and Needles:
18 stitches and 25 rows over 4 inches in Stockinette Stitch on US 6s.

Yarn:
The sample was knit in a worsted weight wool from my stash, purchased as a remnant on a cone. Excellent substitutions include Cascade 220 and Ella Rae Classic Solids and Heathers.
Yardage requirements:
900 (950, 1000, 1100, 1175, 1300, 1350, 1425, 1550) yards

Notions:
Straight or circular needle in size needed to get gauge to work body and sleeves
24” inch circular needle in size needed to get gauge to work collar
Tapestry or darning needle
Two removable stitch markers
Stitch holder or scrap piece of yarn, if desired