1. **State the problem:** We need to find the mode of the number of math teachers in the given high schools. 2. **Recall the definition of mode:** The mode is the value that appears most frequently in a data set. 3. **List the numbers of math teachers:** 6, 6, 4, 5, 6, 4 4. **Count the frequency of each number:** - 6 appears 3 times - 4 appears 2 times - 5 appears 1 time 5. **Identify the mode:** Since 6 appears the most times (3 times), the mode is 6. **Final answer:** The mode of the numbers is $6$.