The Roman numeral equivalent of the number 16 is XVI. The Roman numeral system uses letters to represent numbers. When a letter of lesser or equal value follows a letter, the values are added.
The basic Roman numeral units for numbers through 50 are as follows: I is equal to 1, V is equal to 5, X is equal to 10 and L is equal to 50. The number 16 is equal to 10 + 5 + 1, or XVI. A letter may not appear more than three times in succession. When a letter of lesser value directly precedes a letter of greater value, the one of lesser value is subtracted from the larger number. For example, the number 19 is XIX, where the first X is equal to 10 and the IX represents 10 - 1, for a total of 19.