$11 + 1 = 12$

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Here are 5 related questions for practice:

1. What is $11 + 2$?
2. Solve $12 + 1$.
3. What is the result of $11 - 1$?
4. Calculate $11 + 10$.
5. Solve $11 \times 1$.

Tip: When adding numbers, start from the rightmost digit and move left, carrying over if necessary.