Maths

My 9yo daughter is learning her times tables. It's been hard, but she is so pleased that she knows the answer to '8X7'.

And then today in the office we had a few involved sums to work out. Sarah, my co-worker, immediately reached for the calculator. Accountant Leo suggested that she used a slide rule. She just looked blank - she'd never used one. So I suggested log tables and she admitted that she'd never used them.

Progress?

[tigersaw]

I still use a slide rule. Admittedly never when it matters, but I can always reach an 'ish' answer before everyone else has found their calculator on their phone.

Personally I like steam tables, especially the superheat section.

Slide rule, nope never used one. But good mental arithmetic is a very very useful tool. Being able to know what rough range your answer is meant to be in before you start tapping away at the calculator has saved me making quite a few mistakes

there are rules for them... like, 9 x 7 = 63

to figure it out, you take 1 from whatever number you are multiplying (7-1 = 6) and then put whatever number on the back to make it 9 again (3). 63.

Do you get me?
9 x 9 = (9-1 = 8, 8 + ? = 9, so 9x9 = 81).


2, 3, 4, 5 are all easy. 6 is ok, because you just work what half 12 times is, plus six if its an odd number. 7 is a little tricky, you have to learn that. 8 is easy, evrey time you go up a 10, you go down a 2, 8, 16, 24, 32, 40 and so on. 9 easy, 10 easy, 11 easy, and 12s are fine till you get up there a bit.

I have no memory at all for numbers, tables, formulae, etc but there is a logical way of getting to most of the answers fast.

Duno about this but still know my times tables from 40 odd years ago when I was taught them parrot fashion, as in once 2 is 2, 2 2's are 4 etc can still do up to 12 times table without thinking about it.
Sometimes I even do the days performance figures on paper before running the macro just to keep in practice, all on paper never got on with a slide rule

[northwind]

Originally Posted by rigor

Slide rule, nope never used one. But good mental arithmetic is a very very useful tool. Being able to know what rough range your answer is meant to be in before you start tapping away at the calculator has saved me making quite a few mistakes

Yep, exactly. There was a huge outcry when schools starting teaching approximation techniques a few years back, as if they were saying "nearly is good enough"- it was seen as dumbing down. But approximation's incredibly useful.

I see absolutely no problem with people using calculators either, fwiw, sooner or later we're going to start having wetware upgrades that can do this stuff for us anyway as we ride our hoverbikes. But there's a balance to be struck. Spending months learning times tables by rote isn't too clever either IMO.

im helping a group of kids learn time tables. parrot fashion is one of the best ways to drum it into them. we practice in the playground or gym depending on weather and throw a football to each other as we chant. 9 times table is one of the easiest I find 8 and 7 tricky

Originally Posted by northwind

But there's a balance to be struck. Spending months learning times tables by rote isn't too clever either IMO.

Right. I mean, I am not a particularly stupid person, I am working in a pretty serious lab as their ("lead" apparently) scientific programmer, and contract out to banks and other people. But, I cannot remember the order of numbers. I just can't.

I could never get the tables until I found the patterns in the numbers, and I did maths (even a primary degree in it) in a way that was different to everyone else it seems.
Like northy was saying, I can understand the idea of a concept and then estimate within that range. What I cant estimate, I can brute force with some calculator work, do some estimation, and then work towards an answer. For me, it works, I got a 1.0 in maths.

I suppose it would be nice to be able to learn things by rote, and be able to look up the number 354 in an index and actually go to that page rather than going to 345, but I survive.

[northwind]

Originally Posted by kitkat

9 times table is one of the easiest I find 8 and 7 tricky

Are the kids teaching you?

Thing with rote is that usually you do up to 12x12... Then, someone asks you "what's 13 times 2" and you don't know the answer.