Roman numerals for the 11 plus

Seven letters. I is one, V five, X ten, L fifty, C a hundred, D five hundred, M a thousand. Add them left to right. One rule: if a smaller letter comes before a bigger one, subtract it. I V is five take one, so four. X C is a hundred take ten, so ninety.

D is 500. C, C, two hundreds, so 700. Then X before C: ninety. 790. Then V, I, I, I: five and three ones, eight. 798.

The trap is adding every letter, even the X in front of the C. That gives 818. The small letter in front is the signal to take it away.

Part of the Number & Place Value topics for the 11+.

• 1.1Reading and writing large numbersOne zero can change everything
• 1.2Rounding numbersLook one digit to the right
• 1.3Comparing and orderingThe first difference decides it
• 1.5Negative numbersCrossing zero? Count both sides
• 1.6Prime numbers, factors and multiplesShared factors make it smaller
• 1.7Square and cube numbersA root is not a half
• 1.8Prime factorisationSplit until every end is prime

Every 11 plus maths topic