Number Place (Sudoku) is a puzzle like this.
・Arranging the numbers 1-9 so that they do not overlap in the vertical and horizontal columns.
・The numbers 1-9 must fit within the 3x3 areas without overlapping.

They are often published in puzzle magazines and take a good amount of time to solve.
This app solves that Sudoku in a matter of seconds by entering numbers on the board in the app.

It can also be solved by scanning the Sudoku with the iPhone camera.
There are no examples or practice problems in this app, it is just an app for solving Sudoku.