To Halve or not to Halve... That is the Question. As with the last post, let's begin with a problem. Try and mentally calculate the following division problem:  724898 / 2 .  As before, we will return to this problem at the end.  If you have an even number of items—let's say six jelly beans—and you halve them, then you divide them evenly into two groups—three jelly beans for you and three for a friend. The way we are using it here, you can't halve an odd number. Halving is dividing by two. Only even numbers are divisible by two. As martian mathematics is largely a single-digit technique, we really only need to know how to halve single-digit numbers. We will start with the easy digits: even numbers. Instead of dividing by two, I will denote halving by multiplying by a half. Halving a number with all even digits is as easy as doubling a number with all digits less than five. You can just read off the answer as quickly as you can read off the digits. Let's tr...