diff --git a/src/formatting.rs b/src/formatting.rs
index bf321bc..7c207f5 100644
--- a/src/formatting.rs
+++ b/src/formatting.rs
@@ -3,7 +3,15 @@ use rug::Float;
 use crate::nodes::{self, Error};
 
 pub fn pretty_eval(input: &str, max_digits: usize) -> Result<String, Error> {
-    let (prefix, deliminator, input) = input.rsplit_once_any(&["plus.minus ", "& ", "= "]);
+    let (prefix, deliminator, input) = input
+        .rsplit_once('=')
+        .map(|(p, i)| (p, "= ", i))
+        .unwrap_or_else(|| {
+            input
+                .rsplit_once('&')
+                .map(|(p, i)| (p, "& ", i))
+                .unwrap_or(("", "", input))
+        });
 
     // no need to remove the character here,
     // as we ignore it in all other logic already
@@ -31,26 +39,6 @@ pub fn pretty_eval(input: &str, max_digits: usize) -> Result<String, Error> {
     .replace('e', " * 10^"))
 }
 
-trait StrExt {
-    fn rsplit_once_any<'a>(
-        &'a self,
-        delimiters: &[&'static str],
-    ) -> (&'a str, &'static str, &'a str);
-}
-impl StrExt for str {
-    fn rsplit_once_any<'a>(
-        &'a self,
-        delimiters: &[&'static str],
-    ) -> (&'a str, &'static str, &'a str) {
-        for delimiter in delimiters {
-            if let Some((prefix, suffix)) = self.rsplit_once(delimiter) {
-                return (prefix, delimiter, suffix);
-            }
-        }
-        return ("", "", self);
-    }
-}
-
 pub fn get_significant_digits(n: &Float) -> usize {
     let raw_string = n.to_string().replace('.', "");
 
@@ -87,36 +75,27 @@ pub fn get_significant_digits(n: &Float) -> usize {
 #[cfg(test)]
 mod tests {
     use super::*;
-    const MAX_DIGITS: usize = 10;
     fn eval(s: &str) -> Float {
         crate::nodes::eval(s).unwrap()
     }
 
     #[test]
     fn character_readdition() {
-        assert_eq!(pretty_eval(" = 11", MAX_DIGITS).unwrap(), " = 11");
-        assert_eq!(pretty_eval(" &= 11", MAX_DIGITS).unwrap(), " &= 11");
-        assert_eq!(pretty_eval(" & 11", MAX_DIGITS).unwrap(), " & 11");
-        assert_eq!(pretty_eval(" & 11 \\", MAX_DIGITS).unwrap(), " & 11 \\");
+        assert_eq!(pretty_eval(" = 11", 10).unwrap(), " = 11");
+        assert_eq!(pretty_eval(" &= 11", 10).unwrap(), " &= 11");
+        assert_eq!(pretty_eval(" & 11", 10).unwrap(), " & 11");
+        assert_eq!(pretty_eval(" & 11 \\", 10).unwrap(), " & 11 \\");
     }
 
     #[test]
     fn basic_output_up_to_999() {
-        assert_eq!(pretty_eval("1", MAX_DIGITS).unwrap(), "1");
-        assert_eq!(pretty_eval("10", MAX_DIGITS).unwrap(), "10");
-        assert_eq!(pretty_eval("100", MAX_DIGITS).unwrap(), "100");
-        assert_eq!(pretty_eval("999", MAX_DIGITS).unwrap(), "999");
-        assert_eq!(pretty_eval("1000", MAX_DIGITS).unwrap(), "1 * 10^3");
+        assert_eq!(pretty_eval("1", 10).unwrap(), "1");
+        assert_eq!(pretty_eval("10", 10).unwrap(), "10");
+        assert_eq!(pretty_eval("100", 10).unwrap(), "100");
+        assert_eq!(pretty_eval("999", 10).unwrap(), "999");
+        assert_eq!(pretty_eval("1000", 10).unwrap(), "1 * 10^3");
 
-        assert_eq!(pretty_eval("11.111111", MAX_DIGITS).unwrap(), "11.111111");
-    }
-
-    #[test]
-    fn plus_minus() {
-        assert_eq!(
-            pretty_eval("y & = plus.minus sqrt(15.5) \\", MAX_DIGITS).unwrap(),
-            "y & = plus.minus 3.937003937 \\"
-        );
+        assert_eq!(pretty_eval("11.111111", 10).unwrap(), "11.111111");
     }
 
     #[test]