Picked up this book from and library. I particularly liked this paragraph:
Intuition, in the Star Wars sense, may be the most important and most ignored part of our machine-oriented world. When do you look beyond the rational, the routine, to see what is really around you? Trust your feelings, your “instincts.” In science, you need to know when your equipment isn’t working properly. We’re obsessed with high technology, yet a few bad sensors can cause the meltdown of a megawatt nuclear generator, and a small chunk of foam insulation can destroy a billion-dollar space shuttle and its crew. Skywalker, strong in the Force, knew when to use his computer and when to ignore it. Do we?
And how do you develop this intuition in maths? By immersing yourself in it, by working through pages and pages of calculations and certainly not through using fancy-schmancy calculators!