Origin Story
The "guogu" in jumeok-guogu is none other than the multiplication table (九九). In an age when paper and calculators were scarce, people did their multiplying with nothing but two hands. A clenched fist counted as 5; one finger raised, 6; two, 7; all extended, 10. You added the extended fingers of both hands for the tens place, and multiplied the folded fingers for the ones place. To multiply 7 by 8, for instance, you raised two fingers on one hand and three on the other: (2+3)×10, plus the folded fingers 3×2, came to 56. It was a clever bit of finger-reckoning, but with large or complicated sums it went wrong easily and could not be trusted. So "to figure it out by jumeok-guogu" hardened into the sense of counting roughly on one's fingers — that is, handling something by guesswork, with no solid basis. The old calculator that sat in the palm of a hand has become, today, a byword for "sloppy."
The ingenuity that solved multiplication with ten fingers became, before more precise methods, the very name for "crude." Yesterday's cutting edge often lingers as the next age's guesswork.
Meaning Evolution
How It Is Used
We set the budget by rough guesswork ("jumeok-guogu") and ended up falling far short.
You can't grow a company any further on slapdash, seat-of-the-pants management.
It's a figure estimated off the cuff without solid data, so it's hard to trust.
Related Words
Memory Hook
The multiplication table (九九) done by clenching and opening the fist — fast on the fingers, but too unreliable, so it came to mean "rough."
"The multiplication once solved on the fingers came to be called "rough" before a smarter way of counting."
