By Walt Hickey

Welcome to the Numlock Sunday edition. Each week, I'll sit down with an author or a writer, behind one of the stories covered in a previous weekday edition for a casual conversation about what they wrote.

This week, I spoke to Maya Kosoff who wrote “Big Calculator: How Texas Instruments Monopolized Math Class” for Gen. Here's what I wrote about it:

Texas Instruments has sold the TI graphing calculator in a fundamentally unchanged state for more than a decade, but the price hasn’t noticed: a TI-83+ in 2006 cost about $90, and today it sells for $105, despite the fact that computing technology has taken a substantive leap. Calculators make up less than 3 percent of Texas Instruments’ revenue, but their margins are believed to be considerable. Analysts put the cost to produce a TI-84 Plus at something like $15 to $20, with at least a 50 percent markup conservatively. A PC manufacturer, by contrast, is looking at margins below 3 percent. This markup is passed on to students w…