Convert Microsoft Word old Equations to new format in Word 2013

How can I convert the old Microsoft word equations (version 3) to the new format?

I have an old document file full of equations, and an automatic conversion solution rather than re-typing all equations will be a huge time-saver!

I also tried GrindEq,but word crahes after conversion!

Edit 1: I'm using Microsoft Office Pro Plus 2013 (64-bit) on Win 8.1

Edit 2: I also installed MathType. It supports lots of different formats to convert to, but I could not find Microsoft equation!

Solution 1:

This is a bit lengthy, but it works!

1. Download and LibreOffice. It's free. Only the Windows version works, the Mac (OS X) version won't work (I tried it).
2. Go into Word and save your file as a .doc (if it's not already in that format)
3. Go into LibreOffice, open the .doc file and save it as a .odt file
4. Go into Word, open the .odt file and save it as a .docx

This reduced the file size of some of my Word files with lots of equations by 90%