Answer:
0.879
Explanation:
Tenths are the first position after the decimal point;
Hundredths are the second;
Thousandths are the third;
The number we are after is therefore a number that has 3 digits after the decimal;
What we need to do is consider the digit in the next lower position of value, in this case, the ten thousandths position;
If it is ≥ 5, then you need to round up and if it is ≤ 4, then you need to round down;
In this case, the digit in the ten thousandths position is 9, which is ≥ 5, so we round up;
This means we add 1 to the thousandths digit, which is 8, and that will be the number we want;
This will be: 0.879
If the digit was ≤ 4, then you would need not add or subtract anything and simply write the number as far as the number of decimal places you need.