Not usually. Expressions for decades may be numerals or words (80s, Eighties) A value for a period of years would follow the relevant guide for other numbers, writing out short numbers and those less than 20 or less than 100.
You spelled it correctly. Example Sentence: The 16 year old boy will risk everything to be tennis King of the world!
3 if you spell sentence correct
That is the correct spelling of "sentence."
At the start of a sentence or the beginning of a new sentence
I spell it as T.Shirt when using it as a singular but t.shirt when used in a sentence.
You should spell out the word.
i can spell drowse
Example sentence - The incantation he used for the spell was the wrong one.
You were probably trying to spell synchroniser.An example sentence is "the synchroniser is broken".
If it is ten and over then you spell it. (ten, eleven, twelve...etc.)
I know how to spell the word 'Liveliness'.
Automagically