It is 0.0054 rounded to two significant figures
It is 13000.
Exactly what you typed. 144.78 rounded to 2 decimal places is 144.78. You may mean significant figures, in which case it would be 1.4*10^3 (2 significant figures).
4000 has between 1 and 4 significant figures: if it is a rounded number, then it could have been 3999.9, for example, which would be rounded to 4000 to 1, 2, 3 or 4 significant figures.
0.0062
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
1686 rounded to 2 significant figures is 1700
0.6942 rounded off to 2 significant figures is 0.69
99.9 rounded to 2 significant figures is 1.0e2
6,596 rounded to two significant figures is 6,600
8.0325 rounded to two significant figures results in 8.0.
Rounded to 2 significant figures it is 0.043
There are 2 or 3 significant figures. It could be 894° rounded to 2 significant figures; It could be 889.6° rounded to 3 significant figures.
It is then 0.067 when rounded to 2 significant figures
59,684 rounded to two significant figures is 6.0e4