This is yet one more introductory course on quantum computing. Here I concentrate more on how the mathematical model of quantum computing grows out from physics and experiment, while omitting most of the formulas (when possible) and rigorous proofs. On the first week I try to explain in simple language (I hope) where the computational power of a quantum computer comes from, and why it is so hard to implement it. To understand the materials of this week you don't need math above the school level. Second and third weeks are about the mathematical model of quantum computing, and how it is justified experimentally. Some more math is required here. I introduce the notion of a linear vector space, discuss some simple differential equations and use complex numbers. The forth week is dedicated to the mathematical language of quantum mechanics. You might need this if you want to dig deeper into subject, however I touch only the tip of the iceberg here. On the week 5 I finally introduce some simple quantum algorithms for cryptography and teleportation.