Farmer zulu has a field that's 40 feet long and 15 feet wide. if he wanted to cover the entire field with fertilizer, the number of square yards of fertilizer that he'll need is closest to

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?