We didn’t count, but we know JBW had a huge vocabulary of spoken and spelled words. But what made her brains obvious was how she would figure things out for herself.
For instance, when we got J. Merle as a puppy, JBW stopped playing fetch. Instead, she’d catch the toy, wait for J. Merle to come over and “take” it from her and bring it back to the thrower. IOW, she delegated half of the game.
JBW was also the one who used to throw balls down stairs (pre-J. Merle). Dad decided she needed more exercise than she was getting, so while he was doing laundry, he’d throw a ball up the stairs. JBW would run up and then bring it down, occasionally running back up in anticipation. But on day, the ball came back solo. Dad figured it had just gotten knocked down by accident, so threw it back. JBW caught it, moved to the edge of the top of the stairs, and flipped it forward. As it bounced down, she took up her position for th next throw.
Dad, believing himself smarter than a border collie, subbed a rope bones for balls in stairplay. Initially, JBW was frustrated that the ropes did not roll, so she had to keep following them down as they only went a few stairs when flipped. But eventually, JBW figured out how to flip a rope down stairs, end-over-end, slinky style.
JBW showed J. Merle the basics, and she and C. Merle have both continued the tradition of throwing balls down the stairs, but neither has figured out the slinky rope toss.