diff --git a/input/day7_custom.test.txt b/input/day7_custom.test.txt
new file mode 100644
index 0000000..042be7e
--- /dev/null
+++ b/input/day7_custom.test.txt
@@ -0,0 +1,4 @@
+12345: 12 34 5
+12034050: 120 340 50
+15: 1 2 3 4 5
+120: 1 2 3 4 5
\ No newline at end of file
diff --git a/src/day7.rs b/src/day7.rs
index 12445db..b2e8106 100644
--- a/src/day7.rs
+++ b/src/day7.rs
@@ -1,9 +1,83 @@
 pub fn day7_part1(input: &str) -> String {
     let input = parse(input);
-    let sum: u64 = input.into_iter().filter(|(res, operands)| possible(*res, operands)).map(|(res, _)| res).sum();
+    let sum: u64 = input
+        .into_iter()
+        .filter(|(res, operands)| possible(*res, operands))
+        .map(|(res, _)| res)
+        .sum();
     sum.to_string()
 }
 
+pub fn day7_part2(input: &str) -> String {
+    let input = parse(input);
+    let sum: u64 = input
+        .into_iter()
+        .filter(|(res, operands)| possible_with_concatenation(*res, operands))
+        .map(|(res, _)| res)
+        .sum();
+    sum.to_string()
+}
+
+fn possible_with_concatenation(res: u64, operands: &[u64]) -> bool {
+    let operator_count = operands.len() - 1;
+    let possibilities = 0..(3u64.pow(operator_count as u32));
+    for possibility in possibilities {
+        if evaluate_with_concatenation(possibility, operands) == res {
+            return true;
+        }
+    }
+    dbg!(res);
+    false
+}
+
+fn evaluate_with_concatenation(mut bitpattern: u64, operands: &[u64]) -> u64 {
+    // dbg!(bitpattern, operands);
+    let selected_option = bitpattern % 3;
+    let mut result = if selected_option == 0 {
+        operands[0] + operands[1]
+    } else if selected_option == 1 {
+        operands[0] * operands[1]
+    } else {
+        concatenate(operands[0], operands[1])
+    };
+
+    let mut debug_operators = vec![];
+
+    for operator in 2..operands.len() {
+        bitpattern /= 3;
+        let selected_option = bitpattern % 3;
+
+        result = if selected_option == 0 {
+            result + operands[operator]
+        } else if selected_option == 1 {
+            result * operands[operator]
+        } else {
+            concatenate(result, operands[operator])
+        };
+
+        debug_operators.push(if selected_option == 0 {
+            '+'
+        } else if selected_option == 1 {
+            '*'
+        } else {
+            '|'
+        });
+    }
+
+    // dbg!(result, bitpattern, debug_operators);
+    result
+}
+
+fn concatenate(left: u64, right: u64) -> u64 {
+    let decimal_places_shift = (right as f64).log10().ceil() as u32;
+    left * 10u64.pow(decimal_places_shift) + right
+}
+
+#[test]
+fn test_concatenate() {
+    assert_eq!(concatenate(15, 6), 156)
+}
+
 fn possible(res: u64, operands: &[u64]) -> bool {
     // dbg!(res, operands);
     let operator_count = operands.len() - 1;
@@ -13,7 +87,7 @@ fn possible(res: u64, operands: &[u64]) -> bool {
             return true;
         }
     }
-    
+
     false
 }
 
@@ -41,7 +115,7 @@ fn evaluate(bitpattern: u64, operands: &[u64]) -> u64 {
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
 enum Operator {
     Times,
-    Plus
+    Plus,
 }
 
 fn parse(input: &str) -> Vec<(u64, Vec<u64>)> {
diff --git a/src/lib.rs b/src/lib.rs
index 57a8f40..84761ac 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -356,6 +356,19 @@ mod tests {
         assert_eq!(result, "3598800864292");
     }
 
+    // #[ignore]
+    #[test]
+    fn day7_part2_test() {
+        // let simple_result = day7::day7_part2(include_str!("../input/day7_custom.test.txt"));
+        // assert_eq!(simple_result, (12345 + 12034050 + 15 + 120).to_string());
+
+        // let test_result = day7::day7_part2(include_str!("../input/day7.test.txt"));
+        // assert_eq!(test_result, "11387");
+        let result = day7::day7_part2(include_str!("../input/day7.txt"));
+        let parsed_result: u64 = result.parse::<u64>().unwrap();
+        assert!(parsed_result > 318_910_516_761_637, "{parsed_result} was too low");
+    }
+
     #[test]
     fn day6_part1_test() {
         let test_result = day6::day6_part1(include_str!("../input/day6.test.txt"));