Mental arithmetic learning tools

Abstract

This item is a mental arithmetic learning tool that can improve the user's mental arithmetic ability by rotating four rotating bodies with the numbers 1 to 12 displayed on the outer circumference and mentally calculating the sum of the numbers in a row on each rotating body using addition, subtraction, multiplication, and division. This item has a set of four dodecahedral (decagonal prism) rotating bodies that are individually and rotatably screwed onto a bolt shaft with a screw groove, and a hexagonal prism number-matching nut is rotatably screwed onto the tip of the bolt shaft. There are 12 number faces on the outer circumference of each rotating body, and each number face has a number from 1 to 12 displayed on it. The number-matching nut also has six number faces on the outer circumference, and each number face has a number 24, 36, or 48 displayed on it. An example of how to play is explained. First, the user decides the number of the number-matching nut (24, 36, or 48). Next, the user mentally calculates the total of the numbers in the horizontal row of each rotating body using addition, subtraction, multiplication, division, and sometimes using parentheses, and rotates each rotating body to match the number of the previous number-matching nut. Alternatively, the user decides on any number in the horizontal row of each rotating body, and then decides on the number of the number-matching nut (either 24, 36, or 48). Next, the user mentally calculates the total of the numbers in the horizontal row of each rotating body using addition, subtraction, multiplication, division, and sometimes using parentheses, to match the number of the previous number-matching nut. By playing in this way, the user can improve their mental calculation skills.

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