Take your lump of coal and be grateful...
Jay Nugent 1  20/11/2020 12:11:38 
14 forum posts 2 photos  Spotted the Xmas subscription offer this morning. Somewhat of a maths fail though... £20 does not 37%off of £22.50 make! Edited By Jay Nugent 1 on 20/11/2020 12:12:10 
JasonB  20/11/2020 12:33:45 
Moderator 20248 forum posts 2207 photos 1 articles  But the real art is in being able to read and look at the other numbers, try it based on the cover price of £31.50 for six issues 
J Hancock  20/11/2020 12:46:25 
558 forum posts  Here's one to impress your children. The half times table, the easy way, only 'squared numbers' though. 1 1/2 x 1 1/2 = 2 1/4 Now in all cases subtract 1/2 from first number , add 1/2 to second number, multiply together and add 1/4. So, 7 1/2 x 7 1/2 = 56 1/4 etc, etc.

pgk pgk  20/11/2020 12:49:17 
2073 forum posts 290 photos  J Hancock
Or try to get your kids to use The Trachtenberg Speed system pgk 
not done it yet  20/11/2020 13:12:22 
5776 forum posts 20 photos  Posted by J Hancock on 20/11/2020 12:46:25:
Here's one to impress your children. The half times table, the easy way, only 'squared numbers' though. 1 1/2 x 1 1/2 = 2 1/4 Now in all cases subtract 1/2 from first number , add 1/2 to second number, multiply together and add 1/4. So, 7 1/2 x 7 1/2 = 56 1/4 etc, etc.
Simple one that. The easy way to work out any number squared by using simple algebra.😀 ——— 2 x 2 = ? Easy maths add one and subtract one gives 1 x 3, which is easy maths. Multiply the number added and taken away by itself, so 1 x 1 = 1, which is easy maths Now add the two results together. 3 + 1 = 4, which is easy maths. ——— Easy because you can choose the number added and subtracted to make an easy multiplication for yourself. Derived from (a+b)(ab) which works out as a^2  b^2. You then add b^2 to that answer to find a^2.🙂. Easy, ennit? ——— In your case, the half squared is one quarter. It’s what makes algebra such a useful mathematical tool.😀 
Martin Kyte  20/11/2020 13:41:41 
2309 forum posts 38 photos  5/4 of the population don't understand fractions. :O) Martin

not done it yet  20/11/2020 13:53:57 
5776 forum posts 20 photos  Posted by Martin Kyte on 20/11/2020 13:41:41:
5/4 of the population don't understand fractions. :O) Martin Like “I want my half to be bigger than your half”?🙂 Or even understanding that half the population is below average?🙂 
John Haine  20/11/2020 14:48:59 
3777 forum posts 220 photos  Posted by not done it yet on 20/11/2020 13:53:57:
.....🙂 Or even understanding that half the population is below average?🙂
Sorry to be pedantic but that's half below the median. Same thing for a symmetric distribution but not all distributions are symmetric. 
Paul L  20/11/2020 15:04:59 
57 forum posts 24 photos  According to the governments own figures 27% of children have substandard reading ability. 38% of them cannot write adequately, and the other 39% cannot add up. The youf of today eh.

not done it yet  20/11/2020 15:17:56 
5776 forum posts 20 photos  Posted by John Haine on 20/11/2020 14:48:59:
Posted by not done it yet on 20/11/2020 13:53:57:
.....🙂 Or even understanding that half the population is below average?🙂
Sorry to be pedantic but that's half below the median. Same thing for a symmetric distribution but not all distributions are symmetric. Do you really think that half the population would know the difference between ’mean, median or mode’? If you have a skewed distribution the median can be different from the mean  not what most think of as ‘the average’. The mode could be a long way off with just one very clever individual (unless outliers are ignored), so lets just stick to plain old ‘average’ which most would have some idea of what it means.🙂 
Michael Gilligan  20/11/2020 15:58:10 
17641 forum posts 810 photos  Posted by not done it yet on 20/11/2020 15:17:56:
Posted by not done it yet on 20/11/2020 13:53:57:
.....🙂 Or even understanding that half the population is below average?🙂
[…] so lets just stick to plain old ‘average’ which most would have some idea of what it means.🙂 . .... and has the added advantage of letting you keep repeating your remark. MichaelG. 
Georgineer  20/11/2020 15:59:55 
502 forum posts 30 photos  Posted by Martin Kyte on 20/11/2020 13:41:41:
5/4 of the population don't understand fractions. :O) Martin That's an improper comment! George B. 
Georgineer  20/11/2020 16:22:31 
502 forum posts 30 photos  Posted by J Hancock on 20/11/2020 12:46:25:
Here's one to impress your children. The half times table, the easy way, only 'squared numbers' though. 1 1/2 x 1 1/2 = 2 1/4 Now in all cases subtract 1/2 from first number , add 1/2 to second number, multiply together and add 1/4. So, 7 1/2 x 7 1/2 = 56 1/4 etc, etc. The way I was taught, which amounts to the same thing, was:
I've also found it useful to convert to decimals, as:
Then it can be multiplied by factors of ten, as:
I acquired all sorts of dodges over the years, and it was very gratifying when teaching Astream GCSE pupils to show that I could work out answers on the blackboard while they were still fumbling for their calculators. George B.

Neil Wyatt  20/11/2020 18:56:02 
Moderator 18548 forum posts 723 photos 78 articles  Posted by not done it yet on 20/11/2020 15:17:56:
Posted by John Haine on 20/11/2020 14:48:59:
Posted by not done it yet on 20/11/2020 13:53:57:
.....🙂 Or even understanding that half the population is below average?🙂
Sorry to be pedantic but that's half below the median. Same thing for a symmetric distribution but not all distributions are symmetric. Do you really think that half the population would know the difference between ’mean, median or mode’? If you have a skewed distribution the median can be different from the mean  not what most think of as ‘the average’. The mode could be a long way off with just one very clever individual (unless outliers are ignored), so lets just stick to plain old ‘average’ which most would have some idea of what it means.🙂 If you are talking in terms of IQ, then half the population are below average by definition. This is because IQ tests are calibrated to have a normal distribution centred on 100. Neil 
Jay Nugent 1  20/11/2020 19:12:11 
14 forum posts 2 photos  Posted by JasonB on 20/11/2020 12:33:45:
But the real art is in being able to read and look at the other numbers, try it based on the cover price of £31.50 for six issues But we’re not buying individual issues, we’re buying 6 which retails at £22.50... J 
Kiwi Bloke  20/11/2020 19:40:35 
525 forum posts 1 photos  Posted by Neil Wyatt on 20/11/2020 18:56:02:
Posted by not done it yet on 20/11/2020 15:17:56:
Posted by John Haine on 20/11/2020 14:48:59:
Posted by not done it yet on 20/11/2020 13:53:57:
.....🙂 Or even understanding that half the population is below average?🙂
Sorry to be pedantic but that's half below the median. Same thing for a symmetric distribution but not all distributions are symmetric. Do you really think that half the population would know the difference between ’mean, median or mode’? If you have a skewed distribution the median can be different from the mean  not what most think of as ‘the average’. The mode could be a long way off with just one very clever individual (unless outliers are ignored), so lets just stick to plain old ‘average’ which most would have some idea of what it means.🙂 If you are talking in terms of IQ, then half the population are below average by definition. This is because IQ tests are calibrated to have a normal distribution centred on 100. Neil It's a con trick. IQ test results are ordinally scaled, which means that a symmetrical distribution curve results. Mean and median scores will therefore coincide, and it appears that there are equal numbers of smart and stupid people in the population (without defining 'smart' and 'stupid' because it's difficult...). However, this scaling process is a mathematical 'fudge', and the unequal intervals between the variable's scores ('intelligence' or test results scores) are obscured. There are far more mechanisms around that impair the performance of a complex mechanism than can enhance it (brains are easily damaged or don't develop well) thus the real distribution curve of frequency versus 'intelligence', if the variable 'intelligence' is plotted with a linear scale, is very significantly skewed towards the stupid. However, pointing that out is undoubtedly even less politically correct than pointing out that some people are smarter than others. 
old mart  20/11/2020 20:05:30 
2829 forum posts 178 photos  One thing that annoys me is when a figure of over 100% is mentioned. Even the power of gas turbines is often a figure over 100%. 
John Olsen  20/11/2020 20:47:27 
1155 forum posts 92 photos 1 articles  Gas turbines are a machine that can be run at a higher power than nominal for a short period of time. So if it is rated in terms of maximum continuous power, it may well be capable of more than 100% of that, for a short time. This is actually a useful feature for aircraft, where the ability to get a bit extra for takeoff is quite useful. (Of course they are usually rated in terms of static thrust.) The space shuttle main engines used to be throttled up to more than 100% for some parts of the ascent too. But then that was a pretty dodgy machine at the best of times. John 
Nigel Graham 2  21/11/2020 00:13:17 
1246 forum posts 17 photos  I don't think it's fair to criticise people for not knowing the niceties of Statistics, if like me they have never been taught them, or were taught badly; and are now faced daily with a bewildering assortment of numbers and characteristics only ever described as above, below or at, an unstated " average ". Things like the lowest of a range of three being denoted the "medium ", spring to mind... I don't know what modern school maths syllabi are like, but statistics were not in the GCE OLevel in my generation's time (mid1960s). Or if they were, only to an extremely basic level as in as in 5 being the "average " of 3,4,5,6,7. Nor do I recall Statistics being in a GCSE Course I took for work reasons in the 1990s, although they have a chapter in the set textbook I bought for that course, and still have.
By " taught badly " I mean taught merely a loose assortment of dull topics to be memorised for an exam, rather than also having any meaning in everyday life or work. Often too, the topics presented appear so far removed from many people's lives, that anything beyond basic arithmetic becomes rejected. For example, that GCSE course included Matrices, taught as merely boxes of sums and abstract moves having no purpose, no link to any other mathematics and indeed even having no meaning. (I later learnt elsewhere that Matrices are an ancient Pure Mathematics concept originally called Determinants, but finding a modern use in Finite Element Analysis  hardly a GCSE topic.) The course did not cover all topics in that textbook, which incidentally includes arithmetic of a level many of us would remember from Primary, not Secondary, school! === "Average " .... Having been taught (not " having learnt " French at school because Dorset is nearer to France than to Thirlwall Viaduct, doesn't " average " mean " fair ter middlin' ", or would that be " feeling below median " ? 
Michael Gilligan  21/11/2020 00:30:23 
17641 forum posts 810 photos  Nigel, This is a clear, and mercifully brief, description of the Mean/ Median / Mode https://www.tutor2u.net/geography/reference/meanmedianandmode It is genuinely useful to appreciate the distinction ... Hope it helps MichaelG. 
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