We visited the ATM and withdrew the maximum it would let us - 3 million rupiah - that's about 182 pounds. It was a bit confusing at first dealing with hundreds of thousands of units every day, but we soon got used to it. Very few things cost less than a thousand rupiah (about 6p) anyway so a lot of the time people drop off the word "thousand" for simplicity - although coins for hundreds of rupiah do exist.