The CCA Math Banana$^{\text{TM}}$ costs \$$100$. The cost rises $10$% then drops $10$%. Now what is the cost of the CCA Math Banana$^{\text{TM}}$?

[i]2018 CCA Math Bonanza Lightning Round #1.2[/i]
1. **Initial Cost Calculation**:
   The initial cost of the CCA Math Banana$^{\text{TM}}$ is $100.

2. **First Price Change (Increase by 10%)**:
   When the cost rises by 10%, the new cost can be calculated as follows:
   \[
   \text{New Cost} = 100 + 0.10 \times 100 = 100 \times \left(1 + \frac{10}{100}\right) = 100 \times 1.10 = 110
   \]

3. **Second Price Change (Decrease by 10%)**:
   When the cost drops by 10% from the new cost of $110, the new cost can be calculated as follows:
   \[
   \text{New Cost} = 110 - 0.10 \times 110 = 110 \times \left(1 - \frac{10}{100}\right) = 110 \times 0.90 = 99
   \]

4. **Verification**:
   To verify, we can use the combined percentage change:
   \[
   \text{Final Cost} = 100 \times \left(1 + \frac{10}{100}\right) \times \left(1 - \frac{10}{100}\right) = 100 \times 1.10 \times 0.90 = 100 \times 0.99 = 99
   \]

Thus, the final cost of the CCA Math Banana$^{\text{TM}}$ is $99.

The final answer is $\boxed{99}$.