You added how may mols NaOH? That's M x L = mols.
What final volume do you have. You added 18.01 mL and 10 mL so total volume is 28.01 mL. Convert that to L., then M = mols/L
Do I do 0.1M x .01801L = 0.001801mols?
Then do M = 0.001801mols/0.02801L?
I'm a little confused because I thought I added 0.4503mols when I added 18.01mL
If you added 18.01 mL of 0.1M NaOH you added 0.01801 x 0.1 = ? mols NaOH
Then (NaOH) = mols/L = 0.001801/0.02801 = ?
You may have added 0.4503 mols for all I know since you posted only part of the experiment, but mols NaOH in that particular part is 0.1 x 0.0180 = ?