What is happening
You arrive at a school library counting books back onto the shelves.
Two hundred and fifty books are shelved and the catalogue insists there are four hundred. The rest are still in crates in the corridor.
Place valueRunning
Books shelved
526books
Catalogue total
400books
Number line. Books still in crates at 276 books. Books shelved 526 books, Catalogue total 400 books. Currently books shelved is over by 126 books.
What has to balance