# Rullo solving strategy for 2-4

How to eliminate/nominate candidates without guessing?

For the 3s it's quite easy because of the odd numbers but how to get further?!

For thoose who don't know the game, here's a short introduction:

• The first column must include the 2, but after that it seems difficult. – Jaap Scherphuis Oct 9 '18 at 5:56
• This previous Rullo question includes a description of the rules. – Jaap Scherphuis Oct 9 '18 at 7:48
• what's the '20' on the lower left/right edges? – JonMark Perry Oct 9 '18 at 11:35
• At this point I would probably make a guess, and if that turned out wrong, backtrack. A good option to guess is to include the $4$ in the first column, third row from the bottom (sum $23$). The reason is that this immediately determines that column and row, leading to many forced moves, quickly leading either to a solution or a contradiction. – Jaap Scherphuis Oct 9 '18 at 12:55
• @Dewey823 4+3+4+2+3+2+2 =20. The "target" value for this row is 14. When you press the square with the 14 the tooltip appears which tells you the actual sum of all active candidates. If you press another square the tooltip appears for the other row... – Mat Oct 10 '18 at 7:08

Logic grid puzzles are generally supposed to have a unique solution. This Rullo puzzle has several solutions (unless there is some rule we are missing), so I would consider it an invalid puzzle. Here are four such solutions.

The top two solutions are what I got when I chose to include the 4 in the first column, 3rd row. This eventually (after I think one or two more guesses) led to a situation with only four undetermined cells arranged in a rectangle all with a 2. One diagonal pair had to be included, the other excluded, but both were possible.
The other two solutions are what I got when I chose to include the 4 in the first column, 6th row. This led to about 6 undetermined cells where there were two ways to choose from.
There may be even more solutions.