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Ashwil - I'm not sure I'm getting you.. I wrote it for fun, because I don't know how many kg's there's on a pound...

Don't worry Patrick. I was only joking with you. However, there is an important point within my joke. I am guessing that you are maybe one of the younger contributors here who has only learned metric units of measurement. The practical application of my (lame?) joke is actually very real. There are still large chunks of this world that insist on using imperial measurements such as pounds and miles. Equally, if you follow my example through, you will see that currency conversion also becomes a factor. The lesson is that the real world contains a myriad of situations where the ability to translate readily from one system to another AND to have some basic grasp of the relative scale of measurements can be a huge benefit. Let me give you a genuine example of how this can be useful.

For instance, I am a driver: I live in the UK. We now sell our petrol (gas) in litres, but we are still fixated on gallons and many older drivers still only think in gallons. I know that my car does about 35 miles per gallon (4.54 litres) and the price of the fuel is just over 90 pence per litre. In broad terms,  this gives me a cost of 11p per mile. Now, I also travel frequently to the Philippines, where gas is priced in Pesos and sold in litres. The car only records distance travelled in kilometres. I know that the car does 10km per litre and that the cost is 30 Pesos per litre. The conversion rate of UK pound to Peso varies between about 90 and 100 Pesos to the pound.

Now, I can spend a long while working out exactly what my cost per distance travelled is, but, by having a good awareness of relative scale, I don't need to do that. Indeed, when I am driving, I am concentrating on driving, not on maths! Understanding the relative scales, tells me instantly that the price per litre in the Philippines is only 1/3 of the price in the UK. Hence, as long as the car in the Philippines has no major mechanical problem, I know that it is considerably cheaper to drive there than in the UK.

So, let's return to the apples:

In ganesh's problem, I get 100 apples (at 100g each) for 96 cents. 1 lousy cent each! I am proposing to sell you one pound weight for one pound Sterling. Say £1 = $1.70, then I am offering you approximately 4 1/2 apples for $1.70 when they only cost me 4 cents. In other words, I am ripping you off big time.

So, if you are still studying, then study well and learn the system you are being taught, but don't forget WHY mathematics is important. Understanding relative scale and the art of approxmation are vital skills in everyday life.