It is written as two words if used as a noun: "he entered the house through the back door." It is written as one if used as an adjective: "the Basketball team ran a backdoor play that produced an easy layup."
Nine million one hundred twenty-three thousand seventy-two.
2.105 is written as: two and one hundred five thousandths.
This number is written as: six quintillion two hundred eighty-one quadrillion
One word, two syllables
Literally, "Zero point six nine two." As a fraction, "Six hundred ninety-two one-thousandths."
The word "hairbrush" is typically written as one word, not two.
It is one word.
"Homecooked" is typically written as one word.
The word "underfund" is typically written as one word.
It is one word.
Jackrabbit is typically written as one word.
"Groundwater" is typically written as one word.
It is usually written as one word.
"Westside" is typically written as one word.
"Boomtown" is typically written as one word.
"Skillset" is typically written as one word.
"Teabag" is typically written as one word.