1. **State the problem:** We want to find how many pieces of paper, each with thickness $8.1 \times 10^{-10}$ meters, are needed to make a stack 2 meters high. 2. **Formula:** The total height of the stack is the number of pieces times the thickness of one piece: $$\text{Number of pieces} = \frac{\text{Total height}}{\text{Thickness of one piece}}$$ 3. **Substitute values:** $$\text{Number of pieces} = \frac{2}{8.1 \times 10^{-10}}$$ 4. **Calculate:** $$\text{Number of pieces} = \frac{2}{8.1 \times 10^{-10}} = 2 \times \frac{1}{8.1 \times 10^{-10}}$$ 5. **Simplify denominator:** $$\frac{1}{8.1 \times 10^{-10}} = \frac{1}{8.1} \times 10^{10}$$ 6. **Calculate $\frac{1}{8.1}$:** $$\frac{1}{8.1} \approx 0.12345679$$ 7. **Multiply:** $$2 \times 0.12345679 \times 10^{10} = 0.24691358 \times 10^{10} = 2.4691358 \times 10^{9}$$ 8. **Final answer:** Approximately $$2.47 \times 10^{9}$$ pieces of paper are required to make a 2 meter high stack. This means about 2.47 billion pieces of paper stacked will reach 2 meters high.