Read the Sudoku help page for the rules, and the techniques potentially required to solve BrainBashers Sudoku.
Sudoku is a game of logic - the object is to complete the grid such that every row, every column, and every 3x3 block contains the digits from 1 to 9. There is no mathematics required to solve the puzzles, just pure logic and reasoning.
Each cell is uniquely referenced, e.g. R2C5, for example, means the single cell in Row 2 and Column 5. Also, e.g. Block7 is the block numbered 7.
The 'buddies' of a square are the squares that share a row, column or 3x3 block. e.g. the buddies of R3C7 are shown below.
Every square has 20 buddies.
Note: BrainBashers has a Dark Mode setting.