7 in Roman numerals is VII. The Roman numeral system uses only seven symbols: I, V, X, L, C, D, and M. I represents the number 1, V represents 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. To write 7 in Roman numerals, we can break it down into the sum of numbers 5, 1, and 1, and write their respective equivalent Roman letters to apply the "additive notation". Thus, 7 = 5 + 1 + 1 = V + I + I = VII.