With division, you are essentially looking for how many groups of the divisor (in this case 7) fit into the numerator (in this case 6482)
6482 / 7 = 926
Long division style:
7 does not fit into 2
7 fits into 82 11 times, with a remainder of 5
7 fits into 405 57 times, with a remainder of 6
7 fits into 6006 858 times
11+57+858=926
So, you can easily reverse the process, finding how many groups of 7 it takes to get the larger number. You know that since the 7000 and more than 700 that your solution must be between 101 and 999, trial and error from there. Since it is closer to 7000, try higher numbers, trial and error.