Mental Sums

Anji ate while she browsed through the intermediate spell guidebook her teacher left on the table. She glanced at the counter pebbles piled neatly to one side and wondered if she needed to do more training.

According to the introduction of the intermediate spell guidebook, an advanced mathematical formula was required. There was a concept of quick multiple addition involved called multiplication. Basically, Anji would group the same set of numbers and add them several times over. It was useful when calculating how many sets of spell combinations to repeat in a complicated circuit. 

However, Anji wasn't very good at counting, much less remembering the sum of the last number she calculated. She often lost track of how many times she had counted a repeated number and would make a mistake when tallying the total with the new balance. It was quite the headache.