Numbers in English: Teen vs. Tens and "TY"

Daily I'm starting to be confronted with just what a confusing language English can be. We have crazy spelling, inconsistent rules... (most languages do), but our spelling is just especially confounding because English borrowed from so many languages and made little changes throughout the ages. Anyway, this discussion is about numbers: there is confusion about there about "Teen" and "TY", especially in the situation of talking about years and dates. This how I have chosen to break it down (in Japanese)

Numbers in English: Teens and Tens

Teen: ティン（最後に聞く・言う音 13-19）　 Tens: 最後の聞く・言う音は「ティ」 TY　　

１３　　thirteen 20 twenty (ty)

１４ fourteen 30 thirty (ty)

１５ fifteen 40 forty (ty)

１６ sixteen 50 fifty (ty)

１７ seventeen 60 sixty (ty)

１８ eighteen 70 seventy (ty)

１９ nineteen 80 eighty (ty)

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　９０ ninety (ty)

年を言いたい場合には：

BEFORE　２０００：　２０００年前の年

例：　１９８９　　（１）年を二つに分ける　　（２）番号を一つ一つと言う

　　　　（１）二つに分けたの：　１９　　　８９

　　　　（２）分けた番号を言う：　じゅうきゅう　　はちじゅうきゅう

　　　　（３）英語で言う： nineteen eighty-nine

1988 1949 1984 1999

(Practice)

AFTER 2000: ２０００年のあと

Two thousand ( OO ) と言う　

例：2011 : two-thousand eleven （この場合にも、二つに分ける人もいます）

2012 2013 2014