"Tengo cuatrocientos veinte dólares."
Translation:I have four hundred and twenty dollars.
The "and" is not necessary. In proper English, if you say "and" in a number, it means you are placing a decimal point in the number.
you are absolutely correct! “And” is wrong. With currency it is only used to indicate the cents (decimals).
I was taught in school that it is not optional and that it is flat-out INCORRECT to use the "and".
Could we all please calm down and recognise that numbers in English, like dates and many other concepts, are spoken differently on either side of the Atlantic?
Amd before the police arrive and tell me that this a USA based course, I consider Duolingo's use of multiple dialects to be one its great strengths.
Common speech (in the States, at least) often includes the "and." Math class teaches us that it's improper to do that. "And" is only correctly used between the whole number and the fractional part.