Here's how to get there:

1. Move the decimal point: Move the decimal point three places to the right, so it's after the first non-zero digit (8). This gives you 8.11.

2. Exponent: Since you moved the decimal three places to the right, the exponent is negative and is equal to the number of places moved (3).

3. Combine: Combine the number with the exponent and the unit: 8.11 x 10⁻³ meters.