

じゅうしち日に国へ帰ります。
弟はじゅうしち歳です。
じゅうしち日は誕生日ですか?
"じゅうしち(十七)" is in the lesson "Numbers" (Level 3), along with 19 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.