diff --git a/day9/src/main.rs b/day9/src/main.rs
index b41bd7e..23c1354 100644
--- a/day9/src/main.rs
+++ b/day9/src/main.rs
@@ -10,11 +10,15 @@ fn main() {
     let mut working_vec: Vec<i32> = Vec::new();
     for line in read_to_string("input.txt").unwrap().lines() {
         working_vec.extend(get_numbers_in_line_iter::<i32>(line));
-        let original_length = working_vec.len();
+        let mut extrapolated1 = 0;
+        let mut extrapolated2 = 0;
         let mut sequence_length = working_vec.len() - 1;
         while sequence_length > 0 {
             let mut all_zeros = true;
-            working_vec.push(working_vec[0]);
+            // accumulate last element for task 1
+            extrapolated1 += working_vec[sequence_length];
+            // accumulate first element with subtraction for task 2
+            extrapolated2 = working_vec[0] - extrapolated2;
             for i in 0..sequence_length {
                 working_vec[i] = working_vec[i + 1] - working_vec[i];
                 if working_vec[i] != 0 {
@@ -26,9 +30,10 @@ fn main() {
             }
             sequence_length -= 1;
         }
-        let extrapolated1 = working_vec[sequence_length..original_length].iter().sum::<i32>();
-        let extrapolated2 = working_vec[original_length..].iter().rev().fold(
-            0, |acc, x| x - acc);
+        // flip sign if there was an even amount of elements to account for processing it in reverse
+        if (working_vec.len() - sequence_length) % 2 == 0 {
+            extrapolated2 = -extrapolated2;
+        }
         sum1 += extrapolated1;
         sum2 += extrapolated2;
         working_vec.clear();