わかりましたか。

Japanese always say 「はい、はい、はい、今わかりました。」

• The literal translation is "OK, OK, OK, now I understood." ×
  
• 直訳 (ちょくやく) (n,vs) literal translation; (definition from Edict)
  

However, it's not correct! The sentence contains the word "now", right? If you are talking about now, you should use a present tense. So, instead of saying "I understood", say "I understand". In this case, don't use 現在進行形 (some verbs like this are "understand", "know", and "have").

• 現在進行形 (げんざいしんこうけい) (n) (ling) present continuous tense; present progressive form; (definition from Edict)

Now, everyone say "oh! I understand!"