Rethinking Math

I need to rethink math and my approach with my littlest.  Her brother gets numbers very easily.  It's how his brain works.  He "gets" letters and reads well however he dislikes writing them nicely.  The little one however just goes blank with numbers.  Letters...she's all over them.  Numbers...nope.  She seems to understand patterns/sequence with objects.  Put a number on a piece of paper and she looks/feels lost.