This phrase is signed as "HOW-OLDYOU?" with the wh-word question facial expression (eyebrows down). HOW-OLD is signed by signing OLD twice.
I am 20 years old.
This is signed as "IAGE 20". You learn more about signing ages in ASL 1 - Unit 12.
Money Numbers
Numbers 100+
Ordinal Numbers
These are numbers that show the order of something (for example: winners in a race). Numbers 1st-9th are shown by forming the handshape of the number and twisting the wrist. Every number after 9th is shown by the number + fingerspelling T-H. Even though English gives a number such as 22 an "nd" ending to make 22nd, all numbers after 9th in ASL use "T-H" afterward.
1st-9th = NUMBER + (Wrist Twist) 9th+ = NUMBER + T-H
See you later.
This phrase is signed as: "SEE-YOULATER." The sign SEE moves toward the person you are talking to. The sign LATER is made by taking the L-handshape and moving your wrist from palm-forward to palm-down (it refers to the hands moving on a clock).
Take care of yourself.
This phrase is signed as: "TAKE-CARE". This is like saying "take care!" when you say goodbye in English.