How to Invent Everything: A Survival Guide for the Stranded Time Traveler

by Ryan North

Hindu/Arabic numerals: these are the numbers you’re familiar with: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. You can make up different shapes to represent these numbers if you want; they’re completely arbitrary. Also, as it is now you and not the Hindu and Arabic cultures that are inventing these numerals, you can call them “[Your Name Here] numerals.” In a positional value system: this is where a number’s value is communicated by the position of each digit in the number. For example, 4,023 means “4 thousands, no hundreds, 2 tens, and 3 ones.” This probably sounds pretty familiar, and that’s because positional numbers are the ones you’ve known since you were a kid! Everyone uses them because they rule, and are an extremely efficient and flexible way to represent numbers.* Based on the number 10: our positional system is based on 10, which means each digit in a number is 10 times different than the one beside it. When you move from left to right, each column is 10 times smaller, and when you move from right to left, each column is 10 times bigger. Here’s 4,023 again: 1000s (i.e., 100 × 10) 100s (i.e., 10 × 10) 10s (i.e., 1 × 10) 1s 4 0 2 3 Table 3: There are 4,023 good reasons to study this chart. No, we’re kidding, there aren’t that many. But you will probably still want to briefly glance at it so you can know what a number is.