I is called a loop variable, which is generally assigned to 1, that is, i= 1, but it is related to the content of the loop and may also be assigned to 0 or others.

S is called the summation variable, and if it is summed circularly, it is assigned to 0, and if it is quadrature circularly, it is assigned to 1.

For example, the sum of 1+2+3+ 100, the program is

i= 1

s=0

When I<= 100

s=s+i

Endor

Print s

For example, to find the product of 1 * 2 * 3 * * 100, the program is

i= 1

s= 1

When I<= 100

s=s*i

Endor

Print s