oh good, the .into() can be added even if the type already matches

src/main.rs

@@ -5,7 +5,10 @@ fn main() {
 
     for i in 0..3 {
         println!("a[{i}]: {}", a[i]);
-        println!("a[{i}] * x * y = {}", multiply(a[i], x.into(), y.into()));
+        println!(
+            "a[{i}] * x * y = {}",
+            multiply(a[i].into(), x.into(), y.into())
+        );
     }
 }