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CerberusIV
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Once you can remember all the multiplication tables it is fairly easy to just break larger numbers down.
Example 16*27
16=2*8 and 27=3*9
From memory 8*9=72(I still remember 35 years later)
3*72=210+6=216
2*216=432
so 16*27=432 and it is a lot quicker to think it than type it out.
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Dr. A. Cula
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Looking back at my childhood, I realised I had it quite easy, even if I learned all elementary maths before I actually saw a calculator: my mom's basic profession is maths teacher, and my dad is a railroad cosntruction engineer, so, between the 2 of them they worked out a way to teach me how to do mental calculations even before going to school. Though it must be something in the way the brain works, because the same method failed on my sister.
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Rufus T. Firefly
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is one way of saying it, though I prefer "mensch"
Sep 2000 time: 07:28
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Couldn't agree more, AH; my wife and I face the same uphill battle with our daughter. In her case, it was made worse by the fact that she hates rote work, so crucial aspects of math (like multiplication tables) sent her into fits; I don't think she fully had them down until she was 11, whereas I remember being taught them (and knowing them) at 7 or 8.
Another part of what held her back, though, was how little her teachers expected of her. In the States, with her abyssmal math skills, she was nevertheless an "A" student. But when we moved overseas and enrolled her in an international school with lots of European kids, she found that she knew less than everyone else her age -- and didn't like that feeling one bit. She kicked herself into gear and (many a tearful Daddy/Daughter tutorial later) learned what she needed to. So, as with so many things, I blame America. 
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CerberusIV
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I recently completed a degree in earth sciences (geology related subjects mostly) with the Open University. No calculators allowed although all that the courses required was arithmetic, basic algebra and complex numbers.
Yes, I remember using a slide rule - and largely giving up on it because it was quicker to do work it out in my head.
I haven't seen a slide rule in years but one odd item I discovered tucked away in a corner of the office when I started my present job looks like a slide rule but is specifically for calculating volumes of concrete. By adjusting it for the thickness, length and width, it gives the volume of concrete required. One of my predecessors must have been a civil engineer.
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ravagon
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Australia
Sep 1999 time: 13:28
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quote: Originally posted by Alexander's Horse
I was trying the explain some shortcuts to one of my kids when I was helping him with his homework and he just burst into tears - it wasn't the way he was being taught. He didn't seem to have a concrete idea about numbers in his head the way I do, even when I said stuff like "if you have 6 apples and take away 2, what do you have left?". I had to draw the damn apples!
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I think you may have better luck if you lose the apples. Kids don't 'get' apples. Try jellybeans instead and use props.
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Im very fast at arithmetic also.
Im in math, but as somebody mentionned, that has almost no bearing.
I know ppl with math degrees who take out calculators to add up 2 digit numbers.
I can do quick exact artihmetic (multiplying 2 digits numbers very quickly and such) but maybe from my science background, I can do also rather precise approximations for more complicated stuff, you know converting twice , then multiplying by price and dividing by number of people to estimate what I owe to someone or such. As such, I think this second skill is more useful in day to day life than exact low-level arithmetic, because you can know If something is being charged too much or something like that.
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