Q. Would you spell out 150,000?

A. Use numerals for 150,000. The applicable principles are as follows:

  • Spell out numbers one through one hundred (Chicago’s general rule).
  • Spell out multiples of one through one hundred used in combination with hundred, thousand, or hundred thousand.

So you would spell out “five thousand” and “one hundred thousand” but use digits for 150,000—because 150 would normally be rendered as a numeral.

But if you’re following Chicago’s alternative rule of using digits for 10 and up, all such larger numbers are usually given as numerals. Rather than, for example, “fifteen thousand” or “15 thousand,” you’d write 15,000.

For more details, see CMOS 9.2, 9.3, and 9.4. For numbers with million, billion, and so forth, see CMOS 9.8.