This number, and multiples of this number, are considered lucky because the letters that comprise it spell the hebrew word for life.
What is 18?
The very first letter in the torah, it is also the first letter in every brachah (blessing) that we say.
What is bet? בּ
This was the name of Abraham's first son.
What is Ishmael?
This is the total number of candles that we light during Chanukah. Coincidentally, it's the number of candles contained in each box of them that you buy.
What is 44?
This letter is the first letter in the hebrew word for holy.
What is koof -- as in kodesh ק
These were the names of Isaac and Rebekah's twin sons.
What are Jacob and Esau?
This is the total number of commandments in the torah.
What is 613?
This is the first letter in the hebrew word for Sabbath.
What is shin -- as in Shabbat שׂ
These are the names of Jacob's two wives.
What are Rachel and Leah?
This is the number of books in the torah.
What is 5?
What are aleph and ayin? א ע
This is the name of Israel's first female prophet.
What is Miriam?
This is the total number of books in the Tanach, the complete hebrew bible.
What is 39?
This letter when it appears twice in one word, is the abbreviation for "Adonai"
What is yud? י
This is the prophet whose prediction that "nation shall not lift up sword against nation, neither shall mankind learn war anymore" are inscribed on the entrance to the UN in NYC.
Who is Isaiah?