Question

How do you use a calculator to evaluate the expression `log5` to four decimal places?

Answer 1

`0.698970004 rarr 0.6990`

Explanation:

As there is no base shown, it is assumed that the base is 10.

Calculators have a key: LOG

If you have a D.A.L. calculator the key presses are as follows:

LOG 5 =

The display will be `0.698970004`

The older calculators require the 5 to be entered first and then LOG.
The answer is displayed immediately without =being pressed.

5 LOG

The display will be `0.698970004`

To round to 4 decimal places, consider the value in the fifth place.

`0.6989color(blue)(7)0004`

`7` is more than 5, so the digit to the left will round up.
The `9` becomes 10, meaning the `8` will become `9`.
`(89 rarr 90)`

`0.698color(red)(9)70004` rounds to

`0.6990`

The final `0` must be shown otherwise there will not be 4 places.