840=2 times 2 times 2 times 3 times 5 times 7
Find the median first.
78, 80, 83, 85, 86, 87, 90. The middle one is 85, so there's the median. Take the upper half of this set, not including the median, 85, and then subtract 86 from 90. This is 4, so this is the interquartile range.
The last sentence or second
Four million five hundred and eight thousand three hundred
