You had it right. It is forty.
Forty.
Forty three
five-hunderd forty-eight
Three hundred and forty-nine.
forty, forty-one, forty-two, forty-three, forty-four, forty-five, forty-six, forty-seven, forty-eight, forty-nine, fifty
The number is spelled "forty" everywhere in English.
You spell 340 dollars in English as "three hundred forty dollars." When writing it in a more formal context, you can also use "three hundred forty and 00/100 dollars."
forty three
Forty = vierzig
In British English: "Three hundred and forty-six thousand, seven hundred and twenty-one" In American English: "Three hundred forty-six thousand, seven hundred twenty-one"
You spell it like this: Forty Five dollars.....
That is the correct spelling of "forty" (40).