We prepare 4 levels for assumptions.And the order of assumption is from level1 to level4.In each level you have one chance to suppose the value of all 9X9 cells. for example we suppose the cell of line 5 row 2 with the value of 6.So here the value of level1 is 6 which means the value of line5 row2 may come to the value of 6. Continue to be you can also set the assumption of level2 which is based on level1.For example here we suppose the cell of line 8 row 3 with the value of 3.That means if the level1's assumption is really true the value of line8 row3 may come to the value of 3. Continue to be you can give your assumption based on the previous level until the level of 4.

Step by Step you can up your level to the highest level.On the other hand you can also put down your level. For example if you are now in the level3 and you have not only added several assumptions in level1's chance but also have added several assumptions on level2 and level3's change.If you click level1 button here it means you think the assumptions in level2 and level3 if wrong so you have to give up your efforts during level2 and level3.

Step by Step you can preview the order of cells of each level. For example If you have give 5 assumptions in level1 and you want to know the first order of level1's assumption and the fouth order of level1's assumption.You can click show level1 start point button and you will see the highlight cell of the first order of level1's assumptions.By clicking the "show level1 end point" button and "show level1 prev point" button the fouth order cell of level1 assumption will be highlighted.

Here we introduce the concept of candidate.Which means the candidate assumption of each level. For example if you have already supposed the level1 of the value of 6 in line7 row2.But you also think in this cell the value could be 3,4 or even 8.Here you can input the correspond value in the input form before add candidate of level1 by clicking "add candidate" button of level1. After The candidate be added you can preview the value of candidate in correspond cell by clicking "show candidate" and delete the value of candidate of each level by clicking "delete candidate" button.

Only has the assumption value been added into each level can the candidate value be added into each level's candidate arrays. And only is the assumption value been showing can the "delete candidate" button be effective.