Roman numerals

For grown-ups: this lesson in words

Years 3 to 6 · Maths

Roman numerals: I can read Roman numerals on a clock, to 100 and to 1,000, and read a year written in Roman numerals.

1. The Romans wrote numbers with letters. This clock face has Roman numerals from I to XII.

   I is 1, II is 2, III is 3. The short hand points to III and the long hand to XII: 3 o'clock.

   Now the long hand points to VI: half past. The short hand is between III and IV, so it is half past 3.

   V is 5 and X is 10.

   Picture: A clock with Roman numerals. At first the long hand points to XII and the short hand points to III. Then the hands move on until the long hand points to VI and the short hand is between III and IV.

2. V is 5. Here are 5 counters.

   I is 1. Here is 1 more counter.

   The I comes after the V. A smaller letter after a bigger letter means add.

   VI = 5 + 1 = 6

   Picture: V: 5 counters and I: 1 counter. The groups are pushed together and counted. 6 counters altogether.

3. Here is V again: 5 counters.

   Now the I comes before the V. The crossed-out counter is the I: a smaller letter before a bigger letter means take away.

   IV = 5 − 1 = 4

   So VI is 6, but IV is 4. The order matters.

   Picture: V: 5 counters. 1 counter is crossed out, and 4 are left. 4 left.

4. Your turn: The long hand points to XII, so it is something o'clock. Read the numeral the short hand points to. What time is it?

   Picture: A clock with Roman numerals: the long hand points to XII and the short hand points to IV.

   Choose one:

   • 4 o'clock
   • 5 o'clock
   • 6 o'clock

   Answer

   The answer: 4 o'clock

   4 o'clock. IV = 5 − 1 = 4, so the short hand points to 4.

   Picture: A clock with Roman numerals: the long hand points to XII and the short hand points to IV. The digital time shows 4:00.