PK 2016 Q5
5. Little Lucas invented his own way to write down negative numbers before he learned the usual way with the minus sign in front. Counting backwards, he would write: 3, 2, 1, 0, 00, 000, 0000, …. What is the result of 000 + 0000 in his notation?
- A 1
- B 00000
- C 000000
- D 0000000
- E 00000000
Pink Kangaroo 2016, Question 5. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: C 000000
In Lucas's notation, the first zero represents the minus sign, and the number of other zeroes is the magnitude of the number, so 000 is −2 and 0000 is −3. Then 000 + 0000 is −2 + −3 = −5, which is 000000 in Lucas's notation.
Solution © UK Mathematics Trust, from the PK 2016 solutions.