Rounding to the leftmost digit, calculate the approximate value for the following expressions. \( \begin{array}{llll}\text { a. } 879 & \text { b. } 1788 & \text { c. } 178 \cdot 975 & \text { d. } 78,719+75\end{array} \) a. Using leftmost digit rounding, the sum is approximately \( \square \).

To round to the leftmost digit, we focus on the first significant figure in each number. For \( 879 \), the leftmost digit is \( 8 \), and since there's a \( 7 \) following it, we round up to get approximately \( 900 \). For \( 1788 \), the leftmost digit is \( 1 \), but there’s a \( 7 \) right next to it, so we round up to approximately \( 2000 \). Now for \( 178 \cdot 975 \), we can round them to \( 200 \) and \( 1000 \) respectively, giving us \( 200 \cdot 1000 \approx 200000 \). Lastly, for \( 78,719 + 75 \), rounding to leftmost gives us \( 80,000 + 100 \approx 80,000 \). So, the approximate values would be: a. \( 900 \) b. \( 2000 \) c. \( 200000 \) d. \( 80000 \)