REM Modular inverse
E = 42
T = 2017
GOSUB CalcModInv:
PRINT ModInv
END

CalcModInv:
REM Increments E Step times until Bal is greater than T
REM Repeats until Bal = 1 (MOD = 1) and returns Count
REM Bal will not be greater than T + E
D = 0
IF E < T THEN
  Bal = E
  Count = 1
  Loop:
    Step = T - Bal
    Step = Step / E
    Step = Step + 1
    REM So ... Step = (T - Bal) / E + 1
    StepTimesE = Step * E
    Bal = Bal + StepTimesE
    Count = Count + Step
    Bal = Bal - T
    IF Bal <> 1 THEN Loop:
  D = Count
ENDIF
ModInv = D
RETURN