Write 0.00646 in scientific notation. \[ \square \square \]

To express 0.00646 in scientific notation, you move the decimal point three places to the right, which gives you 6.46. The number of places you moved the decimal becomes the exponent of 10, but since we moved it to the right, it's a negative value. So, 0.00646 in scientific notation is \(6.46 \times 10^{-3}\). Here’s a fun fact: Scientific notation is a lifesaver when dealing with extremely small or large numbers! It allows you to simplify calculations, making it easier for scientists and engineers to communicate their findings without getting lost in zeroes. For a practical example, scientific notation is widely used in fields like chemistry and physics, especially when working with very small quantities like the mass of a hydrogen atom, which is approximately \(1.67 \times 10^{-27}\) kilograms. It keeps everything neat and tidy!