The Roman numeral for \(1\) is \(\mathrm{I}.\)

The Roman numeral for \(5\) is \(\mathrm{V}.\)

The Roman numeral for \(10\) is \(\mathrm{X}.\)

The Roman numeral for \(50\) is \(\mathrm{L}.\)

The Roman numeral for \(100\) is \(\mathrm{C}.\)

When a larger number is followed by a smaller number, the numbers are added.

Example:

\(\mathrm{XV}\) is a \(10\) and a \(5.\) Since the \(5\) comes after the \(10,\) it represents \(10 + 5,\) which is \(15.\)

When a smaller number is followed by a larger number, the smaller number is subtracted from the larger number.

Example:

\(\mathrm{IL}\) is a \(1\) and a \(50.\) Since the \(50\) comes after the \(1,\) it represents \(50 - 1,\) which is \(49.\)

Only one smaller number can come before a larger number. It is used when numbers have a \(4\) or \(9.\)

Example: Write \(23\) in Roman numerals.

The number \(23\) has \(2\) in the tens place. It represents \(20.\) Since \(20\) is \(10 + 10,\) it can be written \(\mathrm{XX}.\)

The number \(23\) has \(3\) in the ones place. Since \(3\) is \(1 + 1 + 1,\) it can be written \(\mathrm{III}.\)

So, \(23\) can be written \(\mathrm{XXIII}.\)

Example: Write \(79\) in Roman numerals.

The number \(79\) has a \(7\) in the tens place. It represents \(70.\) Since \(70\) is \(50 + 10 + 10,\) it can be written \(\mathrm{LXX}.\)

The number \(79\) has a \(9\) in the ones place. Since \(9\) is \(10 - 1,\) it can be written \(\mathrm{IX}.\)

So, \(79\) can be written \(\mathrm{LXXIX}.\)

Example: Write \(246\) in Roman numerals.

The number \(246\) has a \(2\) in the hundreds place. It represents \(200.\) Since \(200\) is \(100 + 100,\) it can be written \(\mathrm{CC}.\)

The number \(246\) has a \(4\) in the tens place. It represents \(40.\) Since \(40 = 50 - 10,\) it can be written \(\mathrm{XL}.\)

The number \(246\) has a \(6\) in the ones place. Since \(6 = 5 + 1,\) it can be written \(\mathrm{VI}.\)

So, \(246\) can be written \(\mathrm{CCXLVI}.\)