Step 1th, open the Word2010 document window, click the formula you want to add a handwritten letter to, and position the insertion cursor in the target location, as shown in Figure 1.
Figure 1 Click the formula you want to add the handwriting letters to
Step 2nd, click the other button in the symbol group in the formula Tools/design ribbon to open the symbol panel, and then click the Drop-down triangle button at the top. Select the handwriting option in the Open Drop-down menu and select the handwritten letter you want in the open Handwriting letter panel, as shown in Figure 2.
Figure 2 Choosing to add a handwriting letter