# What does it mean by the approximate to four decimal place accuracy?

1. Mar 26, 2012

### kougou

【what] does it mean by the term" approximate to four decimal place accuracy"

hey

I have a question. What does it mean by the term " approximate to four decimal place accuracy". For instance, I want to approximate cos(pi/5) to four decimal place using the macluarin series.

The actual value of cos(pi/5) is: 0.809016994

Does this mean that the first five decimal place of the value I obtain from the series must match exactly as 0.80901? What about the rounding?
What if I got something like
1)0.809071
2) 0.809014

Do they still fit into the problem?

2. Mar 26, 2012

### phinds

Re: 【what] does it mean by the term" approximate to four decimal place accuracy"

I think "approximate to 4 decimal places" means 4 significant digits with the last one plus or minus 5, which mean for .809016994, the range of valid answers would be about from .8085 to .8095

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