feat: don't print scientific notation for n < 1000

unfortunately it isn't this easy for n > 0.001,
a similar strategy seems to prefer printing eg 1.0 * 10^-1

src/formatting.rs

@@ -19,10 +19,19 @@ pub fn pretty_eval(mut input: String) -> Result<String, Error> {
         .is_some();
 
     let result = nodes::eval(&input)?;
-    let significant_digits = get_significant_digits(&result).min(MAX_DIGITS);
+    let display_digits = if result >= 1000 || result < 1 {
+        get_significant_digits(&result).min(MAX_DIGITS)
+    } else if result >= 100 {
+        3
+    } else if result >= 10 {
+        2
+    // if result >= 1
+    } else {
+        1
+    };
 
     Ok(format!(
-        "{}{}{result:.significant_digits$}{}",
+        "{}{}{result:.display_digits$}{}",
         " ".repeat(leading_spaces),
         if should_add_back_equals && should_add_back_alignment {
             "& = "
@@ -44,6 +53,14 @@ fn test_character_readdition() {
     assert_eq!(pretty_eval(" & 11".into()).unwrap(), " & 11");
     assert_eq!(pretty_eval(" & 11 \\".into()).unwrap(), " & 11 \\");
 }
+#[test]
+fn test_basic_up_to_999() {
+    assert_eq!(pretty_eval("1".into()).unwrap(), "1");
+    assert_eq!(pretty_eval("10".into()).unwrap(), "10");
+    assert_eq!(pretty_eval("100".into()).unwrap(), "100");
+    assert_eq!(pretty_eval("999".into()).unwrap(), "999");
+    assert_eq!(pretty_eval("1000".into()).unwrap(), "1 * 10^3");
+}
 
 pub fn get_significant_digits(n: &Float) -> usize {
     let raw_string = n.to_string().replace('.', "");