Here's how to get there:

1. Move the decimal point to the right until you have a number between 1 and 10. In this case, we move it 7 places to the right, giving us 2.7.

2. Count the number of places you moved the decimal. This number becomes the exponent of 10. Since we moved it 7 places to the right, the exponent is -7.

Therefore, 0.00000027 is expressed as 2.7 x 10⁻⁷ in scientific notation.