It already is rounded to three significant figures.
2300 rounded to 1 significant figure is 2000.
470 rounded to one significant figure is 500
26112 rounded to one significant figure results in 30000
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.
975 rounded to 1 significant number is 1,000
2,468 rounded to 1 significant number is 2,000
The number 46313 rounded to 1 significant figure is 50000. The significant digit is 5, so the number is rounded up to the nearest power of 10.
It is: 7000 rounded to 1 significant figure
400
0.03
10000
A number with only 1 significant figure can't be rounded to 3 significant figures
It then is: 0.007
10,00010,00010,00010,000
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.
54.26 rounded to 1 significant figure is 50