2.6
1686 rounded to 2 significant figures is 1700
2
12
It is 7500 rounded to two significant figures
5286 you can type "2643*2" into google and it will show you the answer
There are an infinite number of possibilities. For instance, 1000000000 - 99999997357 = 2643 999999999 - 99999997358 = 2643 1 + 2642 = 2643 2 + 2641 = 2643 etc, etc
It is then 0.067 when rounded to 2 significant figures
At least 1 and at most 7. It could be 3,999,999.9 rounded to 7 significant figures; It could be 3,999,999 rounded to 6 significant figures; It could be 4,000,015 rounded to 5 significant figures; It could be 4,000,429 rounded to 4 significant figures; It could be 3,999,999 rounded to 3 significant figures; It could be 4,049,999 rounded to 2 significant figures; It could be 4,492,467 rounded to 1 significant figure.
It is 6.7 when rounded to 2 significant figures
It is 1300 rounded to 2 significant figures
1,430 rounded to 2 significant figures is 1,400
009999991 rounded to 2 significant digits is 1.0e7