2.6
1686 rounded to 2 significant figures is 1700
2
12
0.00245 rounded to one significant figure is 0.002. The first significant figure is '2,' and all digits to the right are replaced with zeros. The leading zeros before the '2' do not count as 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
The rule when rounding off numbers is "If the first figure to be discarded is 5 or more then the previous figure is increased by 1". When 16490 is rounded off to 2 significant figures then the first figure to be discarded is 4. As this is less than 5 then the previous figure (6) is not increased by 1. 16490 to 2 significant figures is 16000.
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 then 0.067 when rounded to 2 significant figures
It is 6.7 when rounded to 2 significant figures
2711 rounded to 2 significant digits is 2700
1,430 rounded to 2 significant figures is 1,400