Math is used in our daily life. Arithmetic operations: +, -, *, and / are the cornerstones of math. Normally, we learn addition first, before the other operations.VHSum reverses the thinking of addition. For example, given the number 26, we would like to determine which numbers in a given group could add up to 26. This is an example of simple logic analysis. This game uses the digits from 2 to 9 and has four levels.1. Beginner level: contains four equations each involving the sum of two numbers.2. Intermediate level: contains six equations each involving the sum of three numbers.3. Advanced level: contains eight equations each involving the sum of four numbers.4. Challenge level: same as the Advanced level with four extra input numbers which can be used.To play, the player swaps the numbers that are used in the equations. The player continues to swap numbers until all equations sum up to their target sums.