Print to serial console from subroutine?

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4

Serial.readStringUntil() - Arduino Reference

Another way:

void loop()
{
  if (verbose) { Serial.print(F("Enter Instruction: ")); }
  Serial.readBytes( Inst, 4);
  Operation = Inst; Operation.trim();

Full code:
Don't Cross The Streams (FP scientific calculator serial co-processor) - Community / Exhibition / Gallery - Arduino Forum