#### You may also like Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself! ### Have You Got It?

Can you explain the strategy for winning this game with any target? ### Counting Factors

Is there an efficient way to work out how many factors a large number has?

# A First Product Sudoku

##### Age 11 to 14 Challenge Level: Like the standard Sudoku, this Sudoku consists of a grid of nine rows and nine columns subdivided into nine 3x3 subgrids.

Like the standard Sudoku, it has two basic rules:
1. Each column, each row and each box (3x3 subgrid) must have the numbers 1 to 9
2. No column, row or box can have two squares with the same number.

The puzzle can be solved with the help of clue-numbers which are small numbers written on the intersections between two cells. Each clue-number is the product of the two digits in the two cells that are on either side of it.

For example, 8 in the top right box means that possible pairs of numbers for the cells above and below are either 1 and 8, 8 and 1, 4 and 2, or 2 and 4 respectively.

You may find it useful to print out a copy of the First Product Sudoku