Regole di Divisibilità
Verifica le regole di divisibilità di qualsiasi numero da 2 a 12.
What are Divisibility Rules?
Divisibility rules are mental shortcuts that determine whether a number divides evenly by another number without performing full division. These rules use digit patterns — last digit, digit sum, or alternating digit sum — to test divisibility by integers from 2 through 12. A divisibility calculator automates all 11 tests at once.
There are 11 standard divisibility rules for divisors 2 through 12. The simplest rules check only the last digit (rules for 2, 5, and 10). The digit-sum rules (for 3 and 9) add all digits. The composite-divisor rules (for 6 and 12) combine 2 simpler rules. The rule for 7 is the most complex, requiring iterative subtraction.
All 11 Divisibility Rules Explained
Divisible by 2
Last digit is even (0, 2, 4, 6, 8).
Rule: Last digit is even (0, 2, 4, 6, 8).
Example: 128 → last digit 8 (even) → divisible by 2.
Divisible by 3
Sum of all digits is divisible by 3.
Divisible by 4
Last 2 digits form a number divisible by 4.
Divisible by 5
Last digit is 0 or 5.
Divisible by 6
Divisible by both 2 and 3.
Divisible by 7
Double the last digit, subtract from remaining digits. Repeat until clear.
Divisible by 8
Last 3 digits form a number divisible by 8.
Divisible by 9
Sum of all digits is divisible by 9.
Divisible by 10
Last digit is 0.
Divisible by 11
Alternating sum of digits (odd position minus even position) is 0 or divisible by 11.
Divisible by 12
Divisible by both 3 and 4.