My academic career was a failure, but fortunately my khanacademic career is skyroketing :-). These days, I watched videos on Thermodynamics (in Chemistry section). I had a deep look at the Carnot Cycle, at adjabatic and isothermic processes and at the entropy definition, and the Maxwell's demon was lurking all the time.
I watched videos in history from French revolution, through Napoleon's rise and until his fall, and I felt sympathetic with people in the Haitian revolution and was scared by the dishonest debt they had to pay until 1947! In my previous history courses I had a more theoretical approach to the French revolution: we discussed in deep all Illuministic theories, but I completeley missed the stuff going on in Europe in 1789-1815. In the end, the Swiss constitution was enforced by Napoleon... I wonder how I could visit London and Paris without knowing what I do now... I practiced with exercises on the Academy site, too. To date, I watched 124 videos and solved 104 exercices. My goal is to earn at least one of the two unknown Black Hole badges!
As my one and one half year old daughter is learning by imitation, I decided to do the same! I equipped myself with an Aiptek 10000U (for about 130 Swiss francs) and bought Screenvideorecorder for another 40 bucks. I then created a tutorial video on how to compute the gamma factor of special relativity. English, audio and overall handling are experimental! (what else would you expect from dangermouse? ;-)
Excel SUMIFS function
It adds the cells in a range (range: Two or more cells on a sheet. The cells in a range can be adjacent or nonadjacent.) that meet multiple criteria. For example, if you want to sum the numbers in the range A1:A20 only if the corresponding numbers in B1:B20 are greater than zero (0) and the corresponding numbers in C1:C20 are less than 10, you can use the following formula:
=SUMIFS(A1:A20, B1:B20, ">0", C1:C20, "<10")
I recently saw SUMIFS used as an extended VLOOKUP with more than one cell which needed to match.