Chapter 1 - Whole Numbers - 1.7 Rounding Whole Numbers - 1.7 Exercises - Page 74: 61

$$ 80,000,000 \\ AND \\ 330,000,000$$

We are asked to round each of the given numbers to the nearest ten million. This means that the first 7 digits (starting from the left) must all be zeros. If the current value of the seventh digit is greater than or equal to 5, then we add 1 to the eight digit. Otherwise, we leave the eighth digit as it is. Doing this, the rounded numbers are: $$ 80,000,000 \\ AND \\ 330,000,000$$