When I did a block of the month, I ended up with 13 blocks. They work out perfectly on point to produce a square piece. Put 9 of the blocks on point in 3 rows of 3. There are now 4 holes. Put the other 4 in those holes and you have it.
Think of our flag. There are 5 rows of 6 stars which makes 30. Then the other stars are fitted into the holes between all these. There just happen to be 20 of those holes. 30 plus 20 = 50.