Calc Ninja: Mental Math Games

Fill in the blanks, build the answer, and slash demons! 30 stages from addition to double brackets. Free mental math training.

Calc Ninja is a mental-math battle puzzle. Fill the blanks in each equation to strike down the oni!

How to play

1. Each battle shows an equation with blank tiles, e.g. ( □ + □ ) × □ = 18.
2. Tap number tiles to fill the blanks so the equation is true.
3. A correct answer strikes the demon; a wrong answer or running out of time lets it strike you.

Content

• 30 scrolls across 6 ninja ranks (Shoden to Gokui)
• 16 unique oni bosses with a demon gallery
• Operators and parentheses stay fixed. You only place the numbers, so it is pure mental math.

Great for

• Adults who want daily brain training
• Anyone who likes number puzzles and quick arithmetic
• Fans of a Japanese ninja-and-oni theme

Free to play. No account required.

• This app is a work of fiction. Characters and story are not based on real people or events.