BristolUK

Certainly working out 10% is easy but deducting something involving a decimal point isn't always that easy in your head.

Ask Anne Aston to do it.

Novocastrian

Yes.

amideislas

Those unfamiliar with the metric system might find it's far simpler than the imperial system.

What I like about the metric system is the predictable divisions and multiplications to arrive at a final number, just by shifting zeros.

How many millimeters in a centimeter? 10. How many centimetres in a meter? 100. How many inches in a yard? (I bet many can't readily answer). How many Meters in a kilometre? How many centimetres is that? How many millimeters is that? How many feet in a mile? how many inches is that?

Also conversion from lengths to volumes. What is the volume of a litre? 1000 cubic centimetres. What is the volume of a quart? Haven't a clue. How many litres in a cubic metre? 1000.

And weights... How much does a cubic centimetre of water weigh? 1 gram. What is the weight of a litre of water? 1 kilogram. What is the weight of a cubic metre of water? 1000 kilograms - or one metric ton.

How many litres are in 15 metric tonnes of water?

Easy peasy....

BristolUK

How many mint imperials to a metric one?

BristolUK

But you understand this sort of thing

Shard

in the past were pupils required to memorise the square roots of numbers like 5 and 7? I was reading a children's story where those questions came up, and it surprised me somewhat.

BristolUK

I was at school 62-73 and I don't remember that. Multiplication tables, yes.

There was a chart on the wall and as each one was done a tick went in that column alongside the child's name.

The 240 pennies, 20/- to a pound etc was memorised, as was a third of a pound. 6s and 8d.

Prime numbers were memorised too.

Bizarrely I changed schools at xmas in the last year at Primary and the new one didn't do such things. Nobody knew what a third of a pound was without calculating it. This new school worked with 'scratch' pens (dipped in ink) whereas we used biros at the previous one.

Alan2005

What's the point thought? They go on forever - probably containing the enitre works of shakespeare in their digits.

scrubbedexpat091

Math is not a strong suit for me, and no reason to hide that and others in the world need to realize math isn't easy for some people, its not an easy subject to learn for some people.

I can do addition, substraction and other basics easily, but more complicated math I need paper, and can figure most things out for + - division and multiplication.

Percents, fractions, algebra and such, haven't a clue for most.

Calculators were never allowed in school, so while they were available in my school days they were not used or permitted in class.

Novocastrian

The handwriting is atrocious but the first equation is the relativistic Doppler Redshift, then a re-formulation of Newtons F=ma in the relativistic frame and at last leads to the famous Einstein equation E=mc^2.

Simple stuff (in hindsight) that I taught to undergraduates only a year ago.It was published 100+ years ago so I'm surprised you haven't come across it before.

The later version develops the General Theory with the result E^2 = m^2c^4 + p^2c^2 where p is the momentum.

BristolUK

We never did that at my comprehensive school or my 'day release' after.

But my handwriting was pretty good.

Shard

I wasn't advocating it, I was just asking some of the more seasoned posters whether that used to be part of the curriculum (in the days before electronic calculators).

dbd33

And we won't, we'll go on enjoying nice round measures until we're 182.88 centiliters under.

Almost Canadian

Wouldn't you need to subtract 32 first, and divide the result by 1.8? Your method doesn't work in the example you gave (the reverse).

Oakvillian

I remember a book of mathematical tables - three-figure solutions for trigonometric functions, square roots, and logarithms (to base 10 and natural logarithms), that I must have used around the ages of 11-13, at which point I was given a scientific calculator one Christmas. It was expensive enough to have been a Christmas present rather than just something I needed for school.

I suspect I was also one of the last school cohorts to be formally taught how to use a slide rule. I don't think I ever used it in anger, but can still more or less remember how to do multiplication and division on a slide rule. We almost certainly didn't need to know for the 1970s curriculum, but my maths teacher presumably thought electronic calculators were a passing fad and we ought to have a fall-back option... Having to do a mental estimation so you know if the answer "looks right" fell out of fashion with the rise of calculators - I'm really happy to see the Ontario elementary curriculum spends quite a bit of time on estimation and mental arithmetic in Grades 4 and 5.

As for Fahrenheit to and from Celcius, rather than messing around with awkward decimals, I find it easier in my head to use vulgar fractions - multiply by 9 and divide by 5 and add 32, or the reverse. Certainly for values within a dozen degrees or so of freezing this makes the mental arithmetic easier. For warmer temps I tend to go upwards or downwards from two convenient and easy to remember fixed conversions - 16C is about 61F, and 28C is about 82F. Just reverse the digits... And if it's really cold the other helpful conversion is the crossover point at -40.