An oblong frame with rows of wires or grooves along which beads are slid, used for calculating

The oblong frame you are referring to is called an abacus. An abacus is a simple mechanical device used for performing arithmetic calculations. It consists of a rectangular frame with multiple rods or wires running parallel to each other.

The rods on the abacus are divided into different units. Each rod represents a specific place value, such as ones, tens, hundreds, and so on. The beads on the rods can be moved back and forth. Typically, there are a certain number of beads above the center bar, representing a value of five, and a certain number of beads below the center bar, representing a value of one.

To perform calculations using an abacus, you slide the beads along the rods according to the desired arithmetic operation. By manipulating the beads and keeping track of their positions, you can add, subtract, multiply, and divide numbers. The position of the beads on the rods represents the numerical values of the calculations.

Abacuses have been used for centuries and have been found in various cultures around the world. They provide a tactile and visual representation of numbers, making them useful for both basic and complex calculations. Although electronic calculators and computers have largely replaced abacuses in modern times, they still hold educational value and are used in some schools to teach mathematical concepts.