diff --git a/regex/src/main.rs b/regex/src/main.rs
index 87cfc22..73ec91b 100644
--- a/regex/src/main.rs
+++ b/regex/src/main.rs
@@ -18,7 +18,7 @@ fn main() {
 
     let re2 = Regex::new(r"(\d+)").unwrap();
     println!("{}", re2.replace_all("Hello 100, 200", | caps: &regex::Captures | {
-        "(".to_owned() + &caps[1] + ")"
+        "(".to_owned() + &(caps[1].parse::<usize>().unwrap() * 2).to_string() + ")"
     }));
     println!("{}", re2.replace_all("Hello 100, 200", | caps: &regex::Captures<'_> | {
         "[".to_owned() + &caps[1] + "]"