vertical-calculation-worksheet

Turn a list of arithmetic problems into a clean, printable A4 vertical-form (竖式) calculation practice sheet for primary-school kids. Reads a JSON problem set of addition, subtraction, multiplication, and division problems, lays them out as a 4×5 grid of standard 竖式 frames (long-division "厂" glyph, carry/borrow space, remainder room), and renders a print-optimized page that exports to PDF. Supports fill-in-blank mode and box (方框) mode for the answer digits. Use this when a teacher or parent wants to hand a child a tidy, uniform stack of 竖式 practice problems to do by hand instead of typesetting them in Word.