"The nearest hundred" means what multiple of 100 is closest to the number. Multiplying 100 by an integer will always give a number with two 0s after it. Clearly, 6800 is the closest.
6799 rounded to the nearest 10 = 6800
7000
853 rounded to the nearest 100: 900. 10853 rounded to the nearest 100: 10900.
100
600
100
100
It is 6800 to the nearest 10 and not 6790
0
555 rounded to the nearest 100 is 600.
97 rounded to the nearest hundred is 100. 97 rounded to the nearest ten is 100
100