Answer
Nearest hundred million: $ 19,700,000,000$
Nearest ten thousand: $ 19,745,620,000$
Nearest billion: $ 19,000,000,000$
Work Step by Step
We are asked to round each of the given numbers to the nearest hundred million. This means that the first 8 digits (starting from the left) must all be zeros. If the current value of the 8th digit is greater than or equal to 5, then we add 1 to the 9th digit. Otherwise, we leave the eighth digit as it is. Doing this, the rounded number is:
$$ 19,700,000,000$$
Using a similar process to round to the nearest ten thousand:
$$ 19,745,620,000$$
Using a similar process to round to the nearest billion:
$$ 19,000,000,000$$