This calculator is so old that they were still experimenting with how the digits should be displayed.. And yes, that is actually how the zero looks. : r/interestingasfuck
Rare Vintage VFD Calculator Sharp Compet CS-2108 Need Repair of 3 buttons | eBay
File:Vintage Radio Shack Electronic Pocket Calculator, Cat. No. 65-638A, Model EC-495, 12 Digit Green VFD, Made in Taiwan, Circa 1978 (11972057203).jpg - Wikimedia Commons
Victor 2640-2 - Printing calculator - VFD - 12 digits - AC adapter - gray - Walmart.com
Retro calculator with VFD display from PulsarLabs on Tindie
VFD Display for the TI83+ Calculator - ATMega32 AVR
RARE Casio FX-39 Scientific Calculator Green VFD Display 1970s Vintage Tested! | Scientific calculator, Calculator, Old technology