title: How to find the smallest triangular number greater than or equal to N?
body: <p>I know how to find the nearest triangular number:
  m = floor(sqrt(2<em>N)
  T = m</em>(m+1)/2
  But that returns the triangular number closest to N.
  I want the nearest triangular number greater than or equal to N.
  So if I input 7, I want 10, not 6.
  Can anyone help me?</p>