1.8 because 0.7 only has 2 signifant figures
That depends on what you want as your rounding. For example, to the nearest 10, it would be 260 and to the nearest 100 it would be 300.
Since the numbers 259 and 1000 share no positive integer factors other than 1, the proper fraction 259/1000 is already expressed in its simplest form.
The only proper factors of 77 are 7 and 11. 11 isn't a factor of 259 but 7 is, so the answer is 7.
The numbers 250-259 can be rounded to 300. Also 301-349 can be rounded down to 300. This works if you are rounding by the nearest hundreds place.
713 + 259 = 259 + x972 = 259 + x713 = x
2592 = 259 x 259 = 67081
274-259
259
36/259 x 100 % = 13233/259 % ≈ 13.9 %
The factors of 259 are 1, 7, 37, and 259. The prime factors of 259 are 7 x 37.
336-259 = 77
259 + 432 = 691