You could use the Calc program. I did one for a friend last using Open Office Calc. I designed the background etc, and used fomule in the spreadsheet to change the date by one day to the required number each month.
you can't...use Microsoft excel.
Microsoft Powerpoint or Openoffice Impress
you can not.
No. When downloaded from the official website, all components of OpenOffice are safe to use.
Yes.
In my opinion you can use shutterfly to design gift calendars. They have various patterns and you can also add your own photos to make it personalized.
You can find templates to make personalized custom calendars at VistaPrint, the Walmart website also will allow you to upload pictures to make your own calendars.
The Olmecs used 3 calendars.
Throw it away and buy the full program or download OpenOffice and use it - OpenOffice is free.
Ancient Hindus generally made use of lunar calendars and solar calendars.
OpenOffice impress is used for openoffice presentations. There are many alternatives to OpenOffice like WPS (has a nice Graphical Interface). "WPS presentation" is used for presentations.
People like the software because it's 'open source' - meaning anyone can make changes to it as they see fit (unlike MS Office which is copyright by Microsoft). OpenOffice is perfectly safe to use.