Rounding off? (1 Viewer)

[ryn101]

Hi, i've recently been really confused on whether to round off an answer before the question is completed or save it in my calculator.

eg (False equation)

1 a) (i)Asks me to find the height of a pole to two decimal places.
(ii) Using the height, find x to two decimal places.

Do i use the answer to (i) to two decimal places for (ii) or do i use the calculator answer say 11.2555292

I don't want to be making such a silly mistake

 

[watatank]

just to be safe use that calculator value. but at the very least at least clearly state that you're using your answer from question one in the next one so they know where you're coming from if you're off.

 

[wogstaa]

Don't round off until the last stage of the answer

 

[ryn101]

Ok thanks alot for your replies

 

[PC]

1 a) (i)Asks me to find the height of a pole to two decimal places.
(ii) Using the height, find x to two decimal places.

RULE: Never round off until the last line of your answer.

It's annoying to have to write down so many decimal places sometimes but thankfully it doesn't happen all that often. Usually you can use the {ANS} button on the calculator to recall the whole number anyway.

For your hypothetical question, go with the calculator until the very last line. Say your height is 21.345286456 metres. Then a new line ... h = 21.35 m. There's your height to 2 decimal places.

ALSO in the majority of cases, you should take the rounded answer into the next part, NOT the long answer. The following questions usually are worked so that the answers work out nicely if you use the rounded answers.

For example, have a look at all the questions which say something like (i) show that x = 4.53, correct to 2 decimal places ... (ii) hence calculate y. This question expects you to use x as 4.53 even though you might calculate it as 4.5300098267.

If that all makes sense.....