The Ending Rules
Drag to inspector
{{ item.val }}
{{ bin.emoji }}
{{ bin.name }}
{{ s1_items.find(i => i.placedBin === bin.id).val }}
✅
Oops! Look closely at the last digit.
The Sum Rule (Rule of 3)
Tap to sum the digits
Tap the digits above...
Is the sum {{ s2_sum }} divisible by 3?
Correct! Because {{ s2_sum }} {{ s2_sum % 3 === 0 ? 'is' : 'is not' }} in the 3 times table, {{ s2_numStr }} {{ s2_sum % 3 === 0 ? 'is' : 'is not' }} divisible by 3.
Unlock the Vault (Rule of 6)
Toggle to unlock. Divisible by 6 means it passes Rule 2 AND Rule 3!
{{ s3_num }}
Rule 2: Is it Even?
Rule 3: Sum div by 3?
Clunk! The handle won't budge. Check your rules.
The Number Grid
Paint all multiples of 9
Hint: Add the digits! Is the sum a multiple of 9?
Not quite! Make sure you only painted numbers whose digits add up to 9, 18, 27, etc.
Perfect! You found them all.
🏆
Master of Divisibility!
You've learned the secret codes to unlock numbers without doing long division.