Calculate how far along you are in a knitting project, assuming linear rate of increases

stitchpercent.py

#!/usr/bin/env python3

def calculate(castOn: int, bindOff: int, totalRows: int, curRow: int):
    incPerRow = (bindOff - castOn)/totalRows; # stitches increased per row
    totalStitches = sum([castOn + incPerRow*r for r in range(1, totalRows)])
    stitchesKnit = sum([castOn + incPerRow*r for r in range(1, curRow)])
    return int(100 * stitchesKnit / totalStitches)

if __name__ == "__main__":
    c = int(input("Stitches cast on: "))
    b = int(input("Final stitch count: "))
    t = int(input("Total rows: "))
    r = int(input("Current row: "))
    print("You are roughly " + str(calculate(c, b, t, r)) + "% of the way done.")