Mr. R.’s World of Math

“That’s a spooky story,” said Zander.
“Yeah, it was so scary in real life,” said Jackie as she hugged her rhino stuffie.
After Jackie’s story, the students all started talking about ghosts and the stuffies they’d brought. I let them chat and told them they had 15 minutes before I turned off the lights. That’s when all talking would have to stop.
After 15 minutes passed, I let everyone get settled in, said good night, and turned off the lights. I was surprised at how quiet everyone was. I lay down on my sleeping bag, and quietly read a book on my phone. After about half an hour, I turned off the phone and lay my head on my pillow.
About a minute later, I heard Jenna whisper, “What’s that?”
“What’s what?” asked Jake.
“That. There’s a glowing light coming from under the closet door.”
I told them to stop talking, but by now everyone was awake again.
“Look, the light’s moving, something’s moving in the closet,” said Joe.
“There’s nothing in the closet,” I assured them, “I’m sure there’s a logical explanation for what you see. Now go back to sleep.” 
“There is something moving in the closet, I’m sure of it, and there’s no logical explanation unless there’s something in there,” said Jenna.
I got up and walked over to the closet, I opened the door and shone the light from my phone in. The closet was empty. 
“See, everyone, there’s nothing in here.” 
“Then what was the light from?” asked Jackie. 
“Your overactive imaginations,” I said, “Now go back to bed, or we won’t be able to wake up in the morning for our special math breakfast.”
“That would be good,” said Carlos, “Who wants to divide the marshmallows in our cereal by the length of our spoons anyway?” 
“Ok, back to bed everyone,” I said.
It was quiet for a while, but then I heard Jenna whisper, “I see the glowing again.”
“Jenna,” I said, “I already told you enough talking.”
But it was too late, and I could see the students begin to look over at the closet. 
“It’s there, the ghost is there, I see it,” said Carlos.
“Don’t be ridiculous guys, there are no such things as ghosts, and even if there were, I doubt they’d want to be in our classroom.”
I walked over to the closet and placed 6 math books on the floor to block out any light the students thought they were seeing.
“Now get back to bed. It’s really late.”

If each of the math books originally had 100 pages, but some of my students had accidentally ripped out 6 pages from each book, how many pages were there left in all 6 books combined?