Fix 2 numbers on tutorial4 doc

docs/beginner/tutorial4-buffer/README.md

@@ -355,7 +355,7 @@ const INDICES: &[u16] = &[
 ];
 ```
 
-Now with this setup, our `VERTICES` take up about 120 bytes and `INDICES` is just 18 bytes given that `u16` is 2 bytes wide. In this case, wgpu automatically adds 2 extra bytes of padding to make sure the buffer is aligned to 4 bytes, but it's still just 20 bytes. All together our pentagon is 134 bytes in total. That means we saved 82 bytes! It may not seem like much, but when dealing with tri counts in the hundreds of thousands, indexing saves a lot of memory.
+Now with this setup, our `VERTICES` take up about 120 bytes and `INDICES` is just 18 bytes given that `u16` is 2 bytes wide. In this case, wgpu automatically adds 2 extra bytes of padding to make sure the buffer is aligned to 4 bytes, but it's still just 20 bytes. All together our pentagon is 140 bytes in total. That means we saved 76 bytes! It may not seem like much, but when dealing with tri counts in the hundreds of thousands, indexing saves a lot of memory.
 
 There are a couple of things we need to change in order to use indexing. The first is we need to create a buffer to store the indices. In `State`'s `new()` method, create the `index_buffer` after you create the `vertex_buffer`. Also, change `num_vertices` to `num_indices` and set it equal to `INDICES.len()`.