The square flags use 16 square feet of fabric per flag because four times four equals <<4*4=16>>16
The wide flags each use 15 feet of fabric per flag because five times three equals <<5*3=15>>15
The tall flags each use 15 feet of fabric per flag because five times three equals <<5*3=15>>15
He has used 256 square feet for the square flags because 16 times 16 equals <<16*16=256>>256
He has used 300 square feet for the wide flags because 20 times 15 equals <<20*15=300>>300
He has used 150 square feet for the tall flags because ten times 15 equals 150.
He has used 706 square feet because 256 plus 300 plus 150 equals <<256+300+150=706>>706.
He has 294 square feet left because 1,000 minus 706 equals <<1000-706=294>>294
#### 294