How many cubes on the pyramid

There was 496 cubes on my answer was 396 so need 100 more cubes.
Lots of people in my class got it wrong.
I counted 11 cubes then I contend all of the 11 rows. Then I contend the second row on the second layer there was 9 cube in a row.
Me and Henry worked together but we did not get the same answer.
Here's my photo.