Gap

Gap is a daily arithmetic game on Mind Loft, played in the browser with no app and no account. Mind Loft calls it the backwards sibling of Blitz: instead of working out the answer to a sum, you are shown the answer and must find the number that has been taken out of the line, as in ? + 6 = 20.

A day's run is twenty problems in five rounds, starting with one-step sums and the times tables and moving on to two-step lines, brackets, percentages, squares, cubes and roots. Each problem gives you four choices and twenty seconds. A correct pick scores a point and moves you on; a wrong pick or a timeout ends the run, and what you cleared is kept as your score.

The wrong choices are built from real slips people make when they run an equation in reverse: adding where they should subtract, dividing the wrong way round, or answering with the result instead of the missing number. That means you cannot guess from the size or last digit of an option, and the reliable check is to put your pick back into the line.

Everyone gets the same twenty problems in the same order, so the daily leaderboard ranks players by how far they got, with ties broken by time. New problems arrive at midnight Eastern, past days are in Mind Loft's archive, and a streak tracks the days you play. Gap is one of five games in Mind Loft's Math Gauntlet, alongside Blitz, Blitzed, Series and Back. It suits anyone who wants a short, timed arithmetic workout with a clear score.