Eight times

Then the cat's senses started sending messages to my brain.

<Whoa!> I yelled in surprise. <Suddenly it isn't nighttime anymore! I mean, wow. Talk about night vision!>

"A cat's vision at night is about eight times stronger than a human's," Cassie said helpfully. "I looked it up."

"Eight times?" Marco repeated. "Not seven, or nine? How do they measure that?"