How is undergraduate economics different from postgraduate economics?

Steven TJ: How is undergraduate economics different from postgraduate economics?
I have done undergraduate economics before – most of it is mainly theory with diagrams and models. There is a lot of rote memorisation and a bit of calculations.
I am now going to start postgraduate studies in economics. I had a look at one postgrad economics exam paper, and I was shocked to see so much mathematics in it – especially calculus and formulas. Especially Hamiltonian and Lagrangian.

My maths isn’t so good especially applied calculus. How can I cope with postgrad economics?

Answers and Views:

Answer by Just did it!
PhD-level economics is indeed all math. Except for Economic History, which isn’t the most demanded branch of economics these days.

Master’s-level is economics is more like undergrad – simple intuition from plots and examples from real life.