After you insert the equation the Equation Tools Design tab opens with symbols and structures that can be added to your. There are multiple equations in the drop-down list then scroll down and select one of them to meet your actual needs. Select Insert Equation or press Alt.
But when you open an existing document created in Word 2003 the equation menu option would be disabled.
Then click the Equation button in the Symbols button group on the right end of the tab. Press Alt and. If you do not find the specified equation under Built-In just click More. Select Save as New Equation from the drop-down list.