Yes, your approach is correct.
Keep in mind, however, that both compounds will contribute to the number of moles of hydroxide ions present in the final solution.
Since you're mixing two strong bases, which by definition dissociate completely in aqueous solution, you'll get
Calcium hydroxide will produce 2 moles of hydroxide ions for every mole of
This means that the total number of moles of
This is the number of moles you'll use for the final concentration of hydroxide ions
In order to avoid a lot of zeroes and ten-powers I usually work with milliMoles (=1/1000 Mole). You will see that in the end the milli's cancel out.
Other note: I use
First solution (
Second solution (
This is in a volume of