Zovo Cross Sum Puzzles

Make printable cross sum puzzles for puzzle fans, teachers and students as a PDF with an answer key, and solve them on screen in the chat card. Zovo Cross Sum Puzzles builds number grids from 6 x 6 to 12 x 12 (counting the clue row and column): fill the white squares with the digits 1 to 9 so that each run of white squares across or down adds up to the sum in the clue square before it, with no digit repeated in a run.

Pick easy, medium or hard. Easy puzzles have short runs of 2 to 4 squares; hard puzzles have runs of up to 5 squares and more white squares. When a hard puzzle cannot be finished within the time limit for a seed, a medium puzzle is made instead and the reply says so.

Before the PDF is made, a solver checks that each puzzle has one solution. The reply lists each puzzle with its size, white squares, number of sums, longest run, and whether it solves by logic alone.

The PDF puts 1, 2 or 4 puzzles on each page, on US Letter or A4, with an optional title and a name and date line for worksheets. Clue squares are dark with a diagonal: the across sum sits above it and the down sum below it. Answer pages at the end show each solved grid. Up to 12 puzzles fit in one PDF.

In the chat card, tap a white square and a digit to fill it in, press Check to see wrong squares, or show the answer.

Each puzzle has a seed. The same seed and settings give the same puzzle again, so a sheet can be reprinted later.

Limitations: grids are square from 6 x 6 to 12 x 12 with runs of 2 to 5 squares, it does not solve a puzzle from a photo or a newspaper, and titles print in Latin, Greek and Cyrillic letters (Chinese, Japanese, Korean, Arabic, Hebrew and emoji are left out of the PDF).