Thankyou both! My mistake was in thinking of .0000004 as being the number that comes before .0000005 when it could actually be say .000000499 which is as close to .0000005 as makes no practical difference for the sake of accuracy, or even .0000004999... repeating which is the same number as...
So if I understand the first part right, you are saying that .234673 correct to 6 significant figures = somewhere between .2346725 and .2346735? (I'm not familiar with lots of these math symbols and am just seeing if I'm reading your meaning right). Is that the actual definition and a number...
My book says:
The bit I don't get is
Why? Apply this logic to one of the numbers at random for arguments sake, let's say the first number .234673, it couldn't be .2346735-.2346739 or else it would have been rounded to .234674. It's true value (if it's greater) has to lie somewhere between...