Question: How do you know if you run out of mana?
Correct answer: Each mage has a different way of telling, depending on how well their mana control is. However, the common symptoms of running low on mana are head-dizziness and fatigue. That usually happens when you have 1/10 of your mana total left, depending on whether you treat it as a pool or a rectangular vase.
Result: Both Zofia and Ashrosaliera got a point.
Ashrosaliera raised her hand.
"Yes?" Thuong asked, eyes up from reading the answer sheet.
"What do you mean… Pool or rectangular vase?" Ash asked.
"Most mages treat mana as a swimming pool, hence the term mana pool, to better mentally visualize the total amount of mana they have, when they used a skill, a part of the water is removed," She answered, continuing "But some placed it all in a small vase for ease of mental visualization, whatever you are, you'll start feeling dizzy at 10% of that pool or vase."