To count the sum of n numbers, you can use a simple algorithm. Here's how it works:

1. Start by initializing a variable called "sum" to 0. This variable will keep track of the running total.

2. Ask the user to input the value of n, which represents the number of numbers they want to sum.

3. Set up a loop that will iterate n times. In each iteration, prompt the user to enter a number.

4. Within the loop, read the input number and add it to the "sum" variable. This will update the running total.

5. After the loop completes, the value of "sum" will be the sum of the n numbers.

6. Display the final sum to the user.

Here's a step-by-step breakdown of the algorithm:

1. Initialize sum = 0.

2. Input the value of n.

3. Set up a loop that iterates n times.

a. Prompt the user to enter a number.

b. Read the input number.

c. Add the input number to sum.

4. Display the value of sum.

That's it! By following this algorithm, you can count the sum of n numbers.