Matrix multiplication is the operation of creating a new matrix from two matrices according to certain rules. The key requirement is that the number of columns in the left matrix must equal the number of rows in the right matrix; otherwise, you can't calculate it. When calculating, the resulting matrix has the same number of rows as the left matrix and the same number of columns as the right matrix, and each element is obtained by multiplying and then adding the corresponding numbers from the row of the left matrix and the column of the right matrix.
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The nine-nine table is what we usually call the nine-nine multiplication table. You memorize it from 'one times one equals one' to 'nine times nine equals eighty-one,' and it's the most basic tool for learning multiplication and division in math.
A nonagon is a closed shape with 9 sides and 9 angles, and the sum of its interior angles is always 1260 degrees.
Precision usually refers to accuracy; it's a combination of how consistent and correct a measurement is, meaning the results are both stable and close to the true value.
Longitude refers to the angle between the plane of the meridian passing through a point on the Earth's surface and the plane of the prime meridian, used to indicate the geographical location east or west on Earth. It ranges from 0° to 180° (east or west longitude). In geography, longitude usually refers to the horizontal coordinate in a spherical coordinate system, specifically the degree to which a location on Earth is east or west of a line called the prime meridian.
Number base calculations mainly involve converting between different bases. The core method is to convert other bases to decimal using 'expand and add by place value,' and convert decimal to other bases using 'divide by the base and take the remainder' or 'multiply by the base and take the integer part.' Binary, octal, and hexadecimal can be quickly converted using the grouping method.
A number system is basically the rule for counting, and the core idea is 'carry over when you reach a certain number.' In daily life, we mostly use the decimal system, while computers use the binary system at the core.
Financial applications usually have two layers of meaning: one is the use of fintech in areas like banking, investment, and risk management, and the other is the financial software or apps that everyday users use. Right now, financial applications are rapidly evolving from digital to intelligent, with AI agents and blockchain technologies becoming core drivers.
There’s a clear difference between data analysis in tech and business, and understanding this gap helps you use tools and methods more accurately.