Question: 
Write a function to find the n-th rectangular number.


Model's Code:
def find_rect_num(n):
    return n * (n + 1) // 2 * 2



Sample Correct Code:
def find_rect_num(n):
  return n*(n + 1) 


Asserts:
assert find_rect_num(4) == 20
assert find_rect_num(5) == 30
assert find_rect_num(6) == 42


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 35 of 974: 27/35 (77.14285714285715%): success