Numbers / 10

The Number 10

10 is composite: factorization 2 × 5. That gives 10 exactly 4 divisors: 1, 2, 5, 10. 10's proper divisors total just 8, 2 short of 10, the deficient case most of 10's neighbors share too. 10 is also the 4th triangular number, the sum of 1 through 4. 10 has a digit sum of 1; for 10, the digital root works out to 1. 10: 2, 5 all divide 10 evenly, out of 2-12. 10 is 1010 in binary and A in hex; as a Roman numeral it's X.