First kids need to be drilled to pick up the basics such as tables of multiplication, the understanding comes afterwards (for some). This is how maths has been taught for ages, but not so long ago common perception under teachers changed: people started thinking, wouldn't it be better to teach kids the ideas and the reasons why basic math rules work, even better, let them discover those rules them by themselves, and get rid of those mind numbing drills?
After a couple of decades, the common perception has switched again: the answer is 'no' [1]. To be able to grasp the ideas behind math rules, your brains have to get familiar with the basic concepts first. And that just takes time and practice. When those basic concepts are engraved in your brain, only then are you able to start playing with them and build higher abstractions.
Learning complex mathematics is not any different.
[1] http://educationbythenumbers.org/content/kumon-worksheet-sty...