Calculation. On its own, this kanji represents this meaning. Although you don’t get to see this kanji on its own fairly often. This kanji usually a part of another compound and lent its “calculation” meaning into it. Examples are:
計 算“Calculation.” Combined with 計 “to measure,” this compound gives a stronger sense of calculation. Should invoke an image of doing the actual calculation. 予 算“Estimate; Budget.” Combined with 予 “prediction,” it is fairly natural to goes from “prediction” and “calculation” to “estimate.” 算 数“Arithmetic.” Combined with 数 “number,” this kanji represents the nightmare for most students. Maths. Calculating number? Maths? Obvious connection.
This kanji is probably divisible into three separate parts shown at the top of this post. The top part of this kanji is a radical for “bamboo.” Basically, whenever you see this on a kanji, it almost always represents a “bamboo” meaning. Observe its resemblance to an actual bamboo from this image.
The middle part of this kanji is said to represent a picture of an “abacus.” And the bottom part of this kanji is said to represent fingers that were using the said “abacus.” It is probably too complicated to draw the individual beads on the abacus and the ten fingers that were using it, so they were simplified as such.
To this day, abacus were still used as a calculator in China. I personally think that the merchants purposely kept this practice of counting with an abacus because it looks cool, and it exudes a certain mystic aura that may help their business. Who knows?
Now because there are still demands for this little thing, some people are undoubtedly made a living by making them. Chances are, you name a material, wood, plastic, stone, metal, even gold, there’s an abacus made from it. But back then, during the time when kanji was invented, abacus was maybe mostly made by the most common material found back then. A bamboo.
And there you have it. An image of fingers, using an abacus, made from bamboo to indicate the meaning of “calculation.”