878 to the nearest 100 is 900. When rounding to the nearest 100, you look at the digit in the tens place. If it is 5 or greater, you round up; if it is less than 5, you round down. In this case, the digit in the tens place is 7, which is 5 or greater, so you round up to the nearest 100, which is 900.
880
1000
percentage = 90.61%% rate:= 878 billion/969 billion * 100%= 0.9061 * 100%= 90.61%
5,878,600,000,000
900
100
That is 4800
4198 to the nearest 100 = 4200
100
100
100
853 rounded to the nearest 100: 900. 10853 rounded to the nearest 100: 10900.