Every run of white squares adds up to the total printed at its head. Digits 1 to 9, and no digit repeats inside a run. A 7×7 board, 26 squares.
Sums is a free daily kakuro from Mind Loft, the cross-sums crossword. Each day gives you a crossword-shaped grid where every run of white squares carries a total in the black square at its head: the across total top right, the down total bottom left. Fill every run with digits 1 to 9 that add up to its total, and never repeat a digit inside a run.
The whole trick is that some totals can only be made one way. Three in two squares is always 1 and 2, sixteen in two is always 7 and 9, twenty-four in three is always 7, 8 and 9. Those fixed runs are your footholds, and where one crosses another run the crossing square usually cracks it. The line under the board lists every digit set that still fits the square you have picked. Every board has a single solution you can always reach by deduction, with no guessing anywhere. Wrong entries are never flagged, so spotting your own slips is part of the puzzle, and because nothing is counted against you the daily leaderboard is a straight race on the clock.
A new grid drops every day at midnight Eastern. Weekdays are 7×7 and step up through the week, and Sundays are an 11×11 Edition. No app, no signup, play free in your browser, keep a streak, and race the leaderboard. Like the arithmetic? Try Cages, the killer sudoku, Sando, the sandwich sudoku, and Crunch, six numbers and one target.