Andrew Hill, age 16, of Asbury Park, N.J. for his question:

WHAT ARE ROMAN NUMERALS?

Roman numerals are symbols that stand for numbers. The system of notation goes back to ancient Roman times.

The Roman numeral system was the most popular form of writing numbers until the widespread use of Arabic numbers in the late 1500s. Today, the Roman system is used to number the faces of some clocks, to list important topics in outlines and to record dates on some public buildings and monuments.

All Roman numerals are written with seven basic symbols: I, V, X, L, C, D and M. There is no zero.

The letter I stands for one, V stands for five, X stands for 10, L stands for 50, C stands for 100, D stands for 500 and M stands for 1,000. All other numbers are written by combining these seven symbols.

Roman numerals are written from left to right, using the principle of addition. You will first write the thousands, then the hundreds, then the tens and finally the units.

To write the number 1985, you first write M (1,000), then CM (which is 900, or 1,000 minus 100), LXXX (50 plus 30) and finally V (5). The date of 1985 appears as MCMLXXXV.

All 4's and 9's use the principle of subtraction. Thus 4 is written as IV, or 5 minus 1, and 9 is written IX, or 10 minus 1.

This principle usually applies to any number beginning with a 4 or a 9, such as 40 (which is written XL or 50 minus 10), 90 (which is written XC or 100 minus 10), 400 (which is written CD or 500 minus 100) and 900 (which is written CM or 1,000 minus 100).

The system of Roman numerals is incovenient and clumsy for most types of calculation. Therefore, it has been replaced almost completely by the easier Arabic numeral system.

Here are some Arabic numbers followed by Roman numerals: 1 is I; 2 is II; 3 is III; 4 is IV; 5 is V; 6 is VI; 7 is VII; 8 is VIII; 9 is IX; 10 is X.

Here are some additional numbers: 11 is XI: 12 is XII; 13 is XIII; 14 is XIV; 15 is XV; 16 is XVI; 17 is XVII; 18 is XVIII; 19 is XIX; and 20 is XX.

And here are some of the bigger numbers:        30    is XXX;    40    is XL;

50    is L;    60 is LX;    70 is LXX:    80 is LXXX;    90 is XC;    100    is C;    200

is CC;        300 is CCC;    400 is CD;    500 is D; 600    is DC;    700    is DCC;     800

is DCCC; 900 is CM; 1,000 is M.

Then go even higher: 2,000 is MM;    3,000 is MMM.

To write larger numbers, a vinculum,    or bar, is placed over a number to multiply it by 1,000.