In formal usage in American English, "and" is reserved to introduce fractional values, and using it anywhere else in the number is *discouraged*. So, the short answer to your question in American English is that not only do you **not have to** put any of those "ands" in there, but people who are finicky about how numbers should be spoken will **love you for leaving it out**. However, if you want to know more about where it can and can't be used in common speech, read on. People often use it before whichever spoken number sounds like it is the last in the list. For example, these are all common: <blockquote>one hundred and one<br> one thousand and ten<br> four thousand and twenty-two<br> one-hundred-and-twelve thousand </blockquote> However, it's unusual to use it before the hundreds place. This sounds a little weird: <blockquote>three thousand and seven hundred</blockquote> It's also unusual to use it between the million and thousands places or the billions and millions places. These all sound weird, too: <blockquote>one million and nine hundred thousand<br> one million and fifty thousand<br> one million and two thousand<br> one billion and six million<br> </blockquote> But using "and" is okay between these large numbers and the tens or ones places: <blockquote>three million and twelve<br> one billion and six</blockquote>