Logaritms.

You can use scientific mode to calculate logs and natural logs.

• To calculate the log (base 10) of a number in formula entry notation mode: tap the log key. log together with an opening bracket will appear in the text entry field. Enter the number, a closing bracket and press Enter.
• To calculate the natural log (base e) of a number in formula entry notation mode: tap the ln key. ln and an opening bracket will appear in the text entry field. Enter the number, a closing bracket and press Enter.