Add submission # 6221

#6221

Author: ArduinoBot

registry.txt

@@ -8072,3 +8072,4 @@ https://github.com/salernosimone/espkit-arduino.git|Contributed|espkit
 https://github.com/salim-mrw/USB-Rubber.git|Contributed|usbrubber
 https://github.com/xreef/MultiFTPServer.git|Contributed|MultiFTPServer
 https://github.com/mobizt/ReadyMail.git|Contributed|ReadyMail
+https://github.com/austin207/ArduinoCalculus.git|Contributed|CalculusCore