What is the value of j as a Roman numeral?

Answer 1

J is not a standard Roman numeral. It was sometimes used as an I.

The letters used are I, V, X, L, C, D, and M.

I = 1

V = 5

X = 10

L = 50

C = 100

D = 500

M = 1000

Larger numbers were created by placing a bar atop the letter to mean 1000's.

Why J was used

The value of J as a Roman numeral was the same as I (1) but it was used on handwritten documents to prevent alteration. For example, the number 6 (VI) could be written as VJ and 7 as VIJ to prevent either from being changed to VIII.