Online shopping is the 'thing' these days and there are a plenty of websites that trick you to buy 10PCS L7815CV TO220 L7815 TO-220 7815 LM7815 MC7815 on-line, but there's non-e that could guide you - giving out the basic fundamentals of buying stuff online. So , assuming that you've got all details packed about the need to purchase your goods online. Mathematics has never been cool, especially for me - so for those like me or even just otherwise I suggest you to understand the math behind the discounts and offers. Take your time - understand the price, the discount and do a few calculations; trust me you'll never go awry. Stop Buying Things You Already Have - The problem with many people is that they tend to buy anything that they like - whether or not they already have it in abundance, which can be never a smart buyer's attribute. So what you need to stop performing immediately is stop buying the things you already have - bear in mind there will be another day so you can get something new the next day.