You can measure many things like a spoon or a fork, maybe even a toaster. If you need a ruler, you may be able to find one online, if you have a phone try that first, or printing one out if possible would be better.
Step-by-step explanation: I started off by guessing a random number, i picked 10. So i multiplied 12x10 and i got 120. I added 120 with 120 until i got something close enough (720.) I got it right on the test as well- :)