400
Every box can hold 1,000 crayons. The students packed the boxes for the teacher.
In the first box, they put 864 crayons.
In the second box, they put 931 crayons.
In the third box, they put 763 crayons.
In the fourth box, they put 881 crayons.
How many more crayons could have been placed in the crayon box then the students placed in them?
What is 561 crayons?