This is a calculation puzzle that numbers disappear when they are added in vertically or horizontally and made 10.
You put number boxes on the squares.
You put number boxes on the squares, and they disappear when they are made 10 in vertically or horizontally.
You'll be happy when a box disappears.
As your level goes up, you also need to use subtraction.
This is suitable to kill time because there is no time limit.
You can play at your own pace by taking a break or continuing on the way.
If your skill goes up, you should challenge in game mode "Hard".