I'm learning number, big numbers like one hundred (100) or one thousand (1000).

The question is: for a composed number e.g. 73,987, that I can write as,
seventy-three thousand, nine hundred and eighty-seven

is the and word mandatory?
or can I simply write seventy-three thousand, nine hundred eighty-seven

another example: 123,601,
one hundred twenty-three thousand, six hundred one
one hundred and twenty-three thousand, six hundred and one

I'm learning number, big numbers like one hundred (100) or one thousand (1000).

The question is: for a composed number e.g. 73,987, that I can write as,
seventy-three thousand, nine hundred and eighty-seven

Is the and word mandatory?
or can I simply write seventy-three thousand, nine hundred eighty-seven

another example: 123,601,
one hundred twenty-three thousand, six hundred one
one hundred and twenty-three thousand, six hundred and one

And if there are differences between British and American English.

I'm learning number, big numbers like one hundred (100) or one thousand (1000).

The question is: for a composed number e.g. 73.987, that I can write as,
seventy-three thousand, nine hundred and eighty-seven

is the and word mandatory?
or can I simply write seventy-three thousand, nine hundred eighty-seven

another example: 123.601,
one hundred twenty-three thousand, six hundred one
one hundred and twenty-three thousand, six hundred and one

I'm learning number, big numbers like one hundred (100) or one thousand (1000).

The question is: for a composed number e.g. 73,987, that I can write as,
seventy-three thousand, nine hundred and eighty-seven

is the and word mandatory?
or can I simply write seventy-three thousand, nine hundred eighty-seven

another example: 123,601,
one hundred twenty-three thousand, six hundred one
one hundred and twenty-three thousand, six hundred and one