For mathematical calculations, such as multiplication and addition, kids can choose different paths to reach the solution :
Recount, Over-count, Decomposition
Commutativity of addition, multiplication
Distribution of multiplication
Multiplicative decomposition

Kids builds paths to find the resolution of equation. Over time, there may be more than one way to solve the same equation. It's the same brain system that relies on weighting and properties. Each node has a value and is linked to other points on the path.

Is this calculation done by our brain faster than a machine or a PC ?
We know that current microprocessors based on binary logic do up to 3 billion instructions per second (3 Ghz).

The brain is more visual than symbolic. He manipulates objects not symbols.

The child begins to count with everyday objects: | | | represent 3 apples, we draw him 3 apples, and next to them numbers 1, 2 and 3.

When the answer is no longer immediate, we can use either automated or thoughtful computation.