Numbers can go on forever—in other words, there are an infinite number of numbers— so no one will ever reach the “highest number.” The highest numbers with which we are most familiar (and can comprehend) include million, billion, and trillion, often referring to such quantities as the number of miles to the outer planets or the federal budget deficit. These larger numbers are usually separated by comma at the thousands, millions, trillions, etc. place values. For example, for 3,490, the comma is after the thousand place value; for 1,384,993, after the million and thousand place value. Larger numbers written for technical papers are sometimes expressed with spaces; for example, 11 384 443 is equivalent to 11,384,443.