Daily Math Puzzle: 2026-10-05
Sharpen your mathematical thinking with fresh puzzles delivered daily.
🧩 New Puzzle Every Day — Free
2026-10-05
A valiant adventurer stands before the fearsome Goblin King, who has only 12 health points remaining. To defeat him, the adventurer must deal at least 12 points of damage. The King offers a choice of two ancient magical runes: 1. **Rune of Swift Strike:** Has a 1/2 chance to deal 10 damage and a 1/2 chance to deal 0 damage on each use. 2. **Rune of Mighty Blow:** Has a 1/3 chance to deal 15 damage and a 2/3 chance to deal 0 damage on each use. The adventurer has time to use runes twice. Which strategy offers the highest probability of defeating the Goblin King?
🔥 Build your streak — solve daily in the app
Solution
Use the Rune of Mighty Blow twice. — Let's break down the probability of success for each strategy:
**Rune of Swift Strike (S):** P(10 damage) = 1/2, P(0 damage) = 1/2
**Rune of Mighty Blow (M):** P(15 damage) = 1/3, P(0 damage) = 2/3
The goal is to deal AT LEAST 12 damage.
**Option 1: Use the Rune of Swift Strike twice.**
Possible outcomes and their probabilities:
- 10 + 10 = 20 damage: (1/2) * (1/2) = 1/4
- 10 + 0 = 10 damage: (1/2) * (1/2) = 1/4
- 0 + 10 = 10 damage: (1/2) * (1/2) = 1/4
- 0 + 0 = 0 damage: (1/2) * (1/2) = 1/4
Only the 20 damage outcome is sufficient (>= 12 damage).
Probability of victory = 1/4 = 0.25
**Option 2: Use the Rune of Mighty Blow twice.**
Possible outcomes and their probabilities:
- 15 + 15 = 30 damage: (1/3) * (1/3) = 1/9
- 15 + 0 = 15 damage: (1/3) * (2/3) = 2/9
- 0 + 15 = 15 damage: (2/3) * (1/3) = 2/9
- 0 + 0 = 0 damage: (2/3) * (2/3) = 4/9
Outcomes sufficient for victory (>= 12 damage): 30 damage, 15 damage (from both combinations).
Probability of victory = P(30 damage) + P(15 damage from 1st hit) + P(15 damage from 2nd hit)
= 1/9 + 2/9 + 2/9 = 5/9 ≈ 0.556
**Option 3: Use the Rune of Swift Strike once, then the Rune of Mighty Blow once.**
Possible outcomes and their probabilities (order doesn't affect total damage):
- S=10, M=15 => Total 25 damage: (1/2) * (1/3) = 1/6
- S=10, M=0 => Total 10 damage: (1/2) * (2/3) = 2/6
- S=0, M=15 => Total 15 damage: (1/2) * (1/3) = 1/6
- S=0, M=0 => Total 0 damage: (1/2) * (2/3) = 2/6
Outcomes sufficient for victory (>= 12 damage): 25 damage, 15 damage.
Probability of victory = P(S=10, M=15) + P(S=0, M=15)
= 1/6 + 1/6 = 2/6 = 1/3 ≈ 0.333
**Comparison:**
- Option 1 (Swift Strike twice): 0.25
- Option 2 (Mighty Blow twice): ≈ 0.556
- Option 3 (Swift Strike once, Mighty Blow once): ≈ 0.333
The highest probability of victory comes from using the Rune of Mighty Blow twice (5/9). This is a tricky problem because both runes have the same average damage per use (Swift Strike: (10*1/2)+(0*1/2)=5; Mighty Blow: (15*1/3)+(0*2/3)=5). However, when considering a specific threshold like 12 damage, the higher potential damage from the Mighty Blow rune, even with its lower individual success rate, makes it more likely to cumulatively exceed the threshold.
Never Miss a Daily Puzzle
Download TestPrepMagic and get push notifications for each day's puzzle. Build daily streaks and track your improvement.
Download Free AppRelated Puzzles
Math Puzzle: 2026-10-04
Deep within the Whispering Caverns, an ancient runic gate blocks your path. To open it, you must complete a sequence of magical engravings. The gate displays the pattern of glowing runes so far:
First, the **Rune of One Sun**.
Next, the **Rune of Two Moons**.
Then, the **Rune of Three Stars**.
Followed by the **Rune of Five Winds**.
And finally, the **Rune of Eight Tides**.
Which rune must be engraved next to unlock the gate?
Math Puzzle: 2026-10-03
A baker is making a special blend of spice mix for his famous gingerbread. The recipe specifies that the amount of cinnamon must be twice the amount of nutmeg, and the amount of ginger must be half the amount of cinnamon. If a full batch of this spice mix, consisting only of these three spices, weighs 420 grams, how many grams of nutmeg are in one full batch?
Math Puzzle: 2026-10-02
You're at the electronics store buying several identical, rectangular boxes for your new home theater system. Each box measures 50 cm long, 30 cm wide, and 20 cm high. Your car's boot (trunk) has internal dimensions of 100 cm long, 75 cm wide, and 50 cm high. What is the maximum number of these boxes you can fit into your car's boot?