The complete set of mathematical formulas for primary school students: the area of the triangle of the definition theorem formula = bottom × height ÷2. Formula S=a×h÷2 square area = side length× side length formula S=a×a rectangular area = length× width formula S=a×b parallelogram area = base× height formula S=a×h interior angle sum: triangle interior angle sum = 180 degrees. Surface (side) area of cylinder: The surface (side) area of cylinder is equal to the perimeter of bottom multiplied by height. Formula: S=ch=πdh=2πrh Surface area of a cylinder: The surface area of a cylinder is equal to the perimeter of the bottom multiplied by the height plus the area of the circles at both ends.

1, additive commutative law: Two numbers are added to exchange the position of addend, and the sum is unchanged. 2. Law of additive combination: When three numbers are added, the first two numbers are added first, or the last two numbers are added first, and then the third number is added, and the sum remains unchanged.