The document provides algorithms and flowcharts for: 1) Finding the average of two numbers by inputting the numbers, adding them, and dividing the sum by 2. 2) Summing the even numbers between 1 and 20 by initializing a sum and counter, adding the counter if it is even, and incrementing the counter until it reaches 20. 3) Finding the sum of the first 50 natural numbers by initializing a sum and counter, adding the counter to the sum, and repeating until the sum reaches 50.