diff --git a/euler51/src/main.rs b/euler51/src/main.rs
index 3db9638..79bf357 100644
--- a/euler51/src/main.rs
+++ b/euler51/src/main.rs
@@ -1,3 +1,4 @@
+mod permutation;
 mod primes;
 
 use crate::primes::Primes;
@@ -12,10 +13,12 @@ const DIGITS: [Int; 10] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
 // const MAX_VALUE: Int = 10_010_000;
 // const MAX_VALUE: Int = 99_999_999;
 
+const LENGTH_OF_NUMBERS: usize = 5;
+const MIN_LENGTH: usize = 2;
+
 fn main() {
     let primes = Primes::get_between(MIN_VALUE, MAX_VALUE);
     // let mut new_primes = primes.clone();
-    println!("{}", primes.vector[0]);
     for p in primes.vector.iter() {
         let mut candidates = vec![];
         let digits = num_to_digits(p);
@@ -41,7 +44,6 @@ fn main() {
     //     println!("{p}");
     // }
 }
-
 fn num_to_digits(n: &Int) -> Vec<Int> {
     n.to_string()
         .chars()
diff --git a/euler51/src/permutation.rs b/euler51/src/permutation.rs
new file mode 100644
index 0000000..1ca36f9
--- /dev/null
+++ b/euler51/src/permutation.rs
@@ -0,0 +1,75 @@
+struct PositionPermut {
+    max_length: usize,
+    number_of_digits: usize,
+    idx: usize,
+    total_number_of_iterations: usize,
+}
+
+impl Iterator for PositionPermut {
+    type Item = Vec<i64>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.idx == (self.total_number_of_iterations) {
+            return None;
+        };
+        let pos1 = self.idx % self.number_of_digits;
+        let pos0 = 0;
+        let x = vec![pos0 as i64, pos1 as i64];
+        let result = Some(x);
+        self.idx += 1;
+        result
+    }
+}
+
+impl PositionPermut {
+    fn new(max_length: usize) -> Self {
+        assert!(max_length >= 3);
+        let total_number_of_iterations = (1..max_length + 1).sum();
+        Self {
+            max_length,
+            number_of_digits: 2,
+            idx: 0,
+            total_number_of_iterations,
+        }
+    }
+    fn test(&mut self) {
+        // length_of_numbers = 4
+        // number_of_digits = 2
+        [0, 1];
+        [0, 2];
+        [0, 3];
+        [1, 2];
+        [1, 3];
+        [2, 3];
+        // number_of_digits = 3
+        [0, 1, 2];
+        [0, 1, 3];
+        [0, 2, 3];
+        [1, 2, 3];
+    }
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_permutation() {
+        use crate::permutation::PositionPermut;
+        use std::collections::HashSet;
+
+        let permutator = PositionPermut::new(3);
+        let result: HashSet<_> = permutator.into_iter().collect();
+        let mut solution = HashSet::new();
+        solution.insert(vec![0, 1]);
+        solution.insert(vec![0, 2]);
+        solution.insert(vec![0, 3]);
+        solution.insert(vec![1, 2]);
+        solution.insert(vec![1, 3]);
+        solution.insert(vec![2, 3]);
+        // solution.insert(vec![0, 1, 2]);
+        // solution.insert(vec![0, 1, 3]);
+        // solution.insert(vec![0, 2, 3]);
+        // solution.insert(vec![1, 2, 3]);
+        // assert_eq!(result.len(), solution.len());
+        assert_eq!(result, solution);
+    }
+}
diff --git a/euler51/src/primes.rs b/euler51/src/primes.rs
index f917140..7402a05 100644
--- a/euler51/src/primes.rs
+++ b/euler51/src/primes.rs
@@ -12,7 +12,10 @@ pub struct Primes<T: Num + ToPrimitive> {
     pub set: HashSet<T>,
 }
 
-impl<T: Num + ToPrimitive + FromPrimitive + Hash + Eq + PartialEq + Copy> Primes<T> {
+impl<T> Primes<T>
+where
+    T: Num + ToPrimitive + FromPrimitive + Hash + Eq + PartialEq + Copy,
+{
     pub fn get_between(min_value: T, max_value: T) -> Self {
         let max_value_usize = max_value.to_usize().unwrap();
         let min_value_usize = min_value.to_usize().unwrap();