Calculator for angles expressed as decimal minutes?

[AntarcticPilot]

What I have seen people do is write tiny little numbers down as they are doing the work on paper. Difficult to explain but I think it goes thus. Lets say subtracting 167 from 252 . Within their head ' seven from two doesn't go, seven from twelve is five - carry one' . Writes little '1' next to the '6'. In head 'One plus six is seven - seven from five doesn't go - seven from fifteen is eight carry one ' writes little '1' next to '1'. Two from two equals zero, answer is eighty five.

Confession time - I couldn't use a scientific calculator to save myself.

It's how everyone older than about 50 was taught to do arithmetic; simple and pretty intuitive. I can't understand the method used by my daughters; it makes no sense to me but is apparently regarded as being more mathematically appropriate, despite being opaque to people who learnt the old way! And actually, the old method using "carrying" digits is how computers do it internally!

 

[mjcoon]

... And actually, the old method using "carrying" digits is how computers do it internally!

Not to mention Babbage's designs before that! (How do abacus users do it?)

 

[AntarcticPilot]

Not to mention Babbage's designs before that! (How do abacus users do it?)

Same way!

 

[finestgreen]

One of the ways children are taught subtraction is the number line. If you want to subtract 23 from 50, you count the number of spaces between 23 and 50; a ten, a ten, seven ones = 27

Handily you probably already carry with you a collection of degree and decimal minute number lines printed on paper and illustrated with weird colourful squiggles

 

[AntarcticPilot]

One of the ways children are taught subtraction is the number line. If you want to subtract 23 from 50, you count the number of spaces between 23 and 50; a ten, a ten, seven ones = 27

Handily you probably already carry with you a collection of degree and decimal minute number lines printed on paper and illustrated with weird colourful squiggles

But the later pencil and paper method that my daughters were taught is opaque to me. Mind, I belong to a generation that was expected to do mental arithmetic by the age of 11!

 

[mjcoon]

But the later pencil and paper method that my daughters were taught is opaque to me. Mind, I belong to a generation that was expected to do mental arithmetic by the age of 11!

Years ago I paid in 3 small cheques without having done the addition in advance. So I watched the cashier doing it (they were not allowed to use a calculator). I could do it in my head, viewing upside down (just the figures, not my head) faster than she could holding the pencil...