The formula of Gauss theorem in primary school refers to the addition of continuous natural numbers, that is, 1+2+3+...+n= (the first term+the last term) * the number of terms /2. Common problems of Gaussian theorem for extended data

1+2+3+...+n=n(n+ 1)/2

1/( 1+2+3+..+n)= 2/[n(n+ 1)]= 2[ 1/n- 1/(n+ 1)]

1+ 1/( 1+2)+ 1/( 1+2+3)+ 1/( 1+2+3+4)+……+ 1/( 1+2+3+4+……+ 100)

=2[ 1- 1/2+ 1/2- 1/3+ 1/3-+ 1/ 100- 1/ 10 1]

=2* 100/ 10 1

=200/ 10 1

Calculation formula of common geometry in primary school mathematics

1, perimeter of rectangle = (length+width) x2C=(a+b)x2.

2. The circumference of a square = the side length x4C=4a.

3. area of rectangle = length x width S=ab

4. Area of square = side length x side length S = axa = square.

5. Area of triangle = base x height +2S=ah+2.

6. area of parallelogram = bottom x height S=ah

7. Trapezoidal area = (upper bottom+lower bottom) x height +2S=(a+b)h+2.