calcuting what an extra 30% is???

[BigT]

If I was working it out in my head, the way I would do it is this:

30% = 3 x 10%.
10% of £50 is £5.
3 x £5 = £15.
£50 + £15 = £65.

I find it easier to break calculations down into a string of simpler calculations when I'm doing them in my head. With a calculator, I'd just do 50x1.3 = 65.

That's exactly how I would do it in my head and pretty much the way I approach every piece of mental arithmetic. I credit my junior school maths teacher who taught this way of solving simple equations. This was back in the 80s when you didn't have to slavishly follow a curriculum at that age, nor sit SATs or whatever other exams poor kids get measured by at 9 years old these days. He was a huge influence in the two years he taught me and as well as teaching me this way of thinking probably gave me my fondness of mathematics which lead me to study it at University and then go into the tech industry.

 

[Van_Dammesque]

Percentages are mathematically easy, the problem people have with percentages is the language used as caveats.
This is not taught thoroughly in schools.

EDIT: I can't believe this thread is 4 pages long!