唯一数（Last Value）
在数独解题中有一种最简单的技巧，当某行（列、宫）的其他八格已填上数之后，那么还剩的宫格的数通过点算即可得到。
下面我们来看一道例题。例如看第五宫，还剩一个宫格，点算一下应该是几呢？（点击盘面可显示答案）
| C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | C9 | |
| R1 | 4 | 1 | 2 | 5 | 6 | 8 | 7 | 9 | |
| R2 | 8 | 6 | 4 | 7 | 2 | 5 | |||
| R3 | 5 | 3 | 1 | 2 | 4 | ||||
| R4 | 7 | 5 | 2 | 4 | 9 | 3 | 8 | 6 | |
| R5 | 2 | 9 | 6 | 3 | 5 | 1 | 4 | ||
| R6 | 3 | 6 | 4 | 7 | 1 | 8 | 2 | 9 | |
| R7 | 5 | 3 | 9 | 7 | 6 | ||||
| R8 | 8 | 1 | 2 | 7 | 4 | 5 | |||
| R9 | 2 | 4 | 7 | 5 | 6 | 9 | 1 | 8 |
再来看看第一行，空格处是几呢？（点击盘面可显示答案）
| C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | C9 | |
| R1 | 4 | 1 | 2 | 5 | 6 | 3 | 8 | 7 | 9 |
| R2 | 8 | 6 | 4 | 7 | 2 | 5 | |||
| R3 | 5 | 3 | 1 | 2 | 4 | ||||
| R4 | 7 | 5 | 2 | 4 | 9 | 3 | 8 | 6 | |
| R5 | 2 | 9 | 6 | 3 | 5 | 1 | 4 | ||
| R6 | 3 | 6 | 4 | 7 | 1 | 8 | 2 | 9 | |
| R7 | 5 | 3 | 9 | 7 | 6 | ||||
| R8 | 8 | 1 | 2 | 7 | 4 | 5 | |||
| R9 | 2 | 4 | 7 | 5 | 6 | 9 | 1 | 8 |
再来观察第二列，空格处是几呢？（点击盘面可显示答案）
| C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | C9 | |
| R1 | 4 | 1 | 2 | 5 | 6 | 3 | 8 | 7 | 9 |
| R2 | 8 | 6 | 4 | 7 | 2 | 5 | |||
| R3 | 5 | 3 | 1 | 2 | 4 | ||||
| R4 | 7 | 5 | 2 | 4 | 9 | 3 | 8 | 6 | |
| R5 | 2 | 9 | 6 | 3 | 5 | 1 | 4 | ||
| R6 | 3 | 6 | 4 | 7 | 1 | 8 | 2 | 9 | |
| R7 | 5 | 3 | 9 | 7 | 6 | ||||
| R8 | 9 | 8 | 1 | 2 | 7 | 4 | 5 | ||
| R9 | 2 | 4 | 7 | 5 | 6 | 9 | 1 | 8 |
下面提供一些用唯一数法即可完成的练习题目（点击题目即可复制，之后可以到 演练场 的自定义模式中粘贴，确定后可直接生成对应的题目）：
| 412560879086472500053001024075249386029605140364718290530900760008127450247056918 |
| 930856412461907850250341906080014205610205087705630040806473021042109738173582094 |
| 679301408350780261182504973421853000035000120000142385298405617513076049706908532 |
| 084203571203517094070098236357042160408601702021870349816750020530124607742306910 |
| 109805736060019802785632019900563178850901064617284003470356921506120040231407605 |
| 456301082073205641812647005648750093020904060390016274500478329289103450730509816 |
| 096437018148009307023618490005174932071903650439526700057862140602300879380791520 |
| 890052617275609004060407295637590128048203570952071436489105060500708943723940051 |
| 067003501351867020248095670126509834089201750735608912074380195010954267502700340 |
| 072849516904205078806071942530726100049508230007493085263180709490607801781952460 |
| 810249356200810749394705018436008197002901600981600532570106423123097005648352071 |
| 267103040850406712914728600608015374571000926439260105006572438382601097040809261 |
| 060034205153729640942586730605093412300201006214650309086315927031972864709460050 |
| 762084951009650874485091630910278540508000703047135089054810397391027400876940125 |
| 209003805743805219580029670128754906304206107605391428052640091437908562906500704 |
| 908367502635094108427581903243600010509708204070003659702146385306970421104832706 |
| 465839170890275030703064985207601850649000321058903607374590208080412093012387564 |
| 143508002980074316762930580834150697007406100651093248076015429419620035500309761 |