diff --git a/questions/006-value-of-assignment.md b/questions/006-value-of-assignment.md
new file mode 100644
index 0000000..2f53520
--- /dev/null
+++ b/questions/006-value-of-assignment.md
@@ -0,0 +1,39 @@
+Answer: 0
+Difficulty: 1
+
+# Hint
+
+There are two variables named `a`. What is the type of each one?
+
+# Explanation
+
+There are two variables named `a`, one shadowing the other. The program is
+equivalent to:
+
+```rust
+let a;
+let b = a = true;
+print!("{}", mem::size_of_val(&b));
+```
+
+Further, the value being assigned to `b` is the expression `a = true`.
+
+In Rust, assignment expressions always have the value `()`. Simplified some
+more, the quiz code is equivalent to:
+
+```rust
+let a = true;
+let b = ();
+print!("{}", mem::size_of_val(&b));
+```
+
+Refer to the documentation of [`size_of_val`] for a specification of its
+behavior, but in this case it is being instantiated with `T = ()` and we end up
+printing the value of `size_of::<()>()`.
+
+[`size_of_val`]: https://doc.rust-lang.org/std/mem/fn.size_of_val.html
+
+`()` is one example of a [*zero-sized type*][zst] or ZST and is represented by
+zero bytes of data at runtime, so the program prints `0`.
+
+[zst]: https://doc.rust-lang.org/nomicon/exotic-sizes.html#zero-sized-types-zsts
diff --git a/questions/006-value-of-assignment.rs b/questions/006-value-of-assignment.rs
new file mode 100644
index 0000000..029e410
--- /dev/null
+++ b/questions/006-value-of-assignment.rs
@@ -0,0 +1,7 @@
+use std::mem;
+
+fn main() {
+    let a;
+    let a = a = true;
+    print!("{}", mem::size_of_val(&a));
+}