4 because in the English language, every other number can be reduced to four by a simple system of writing and counting.
Take literally any number you'd like, don't make it too long, you're going to have to write it out. Say... 5,050 Now, write out that number in English. "Five thousand, Five Hundred" Count the letters in the name for that number, in this case 23 letters. Then write out that number. "Twenty-Three" Repeat. Continuing the example: "Twenty-Three" has 11 letters, written as "Eleven", which has 6 letters, written as "Six" which has 3 letters, written as "Three", which has 5 letters, written as "Five", which has 4 letters, written as "Four". That's where it stops because four is the only number in the English language that has the same amount of letters in its name as the quantity it represents. This trick works for any number of any size, so long as you write it in English and are willing to do the work to write all of it out.
Top that, number 23!
