GK 2018 Q4
4. Which number should replace the symbol * in the equation 2 × 18 × 14 = 6 × * × 7 to make it correct?
- A 8
- B 9
- C 10
- D 12
- E 15
Grey Kangaroo 2018, Question 4. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: D 12
Write each number in the expression as a product of prime factors to obtain 2 × 2 × 3 × 3 × 2 × 7 = 2 × 3 × * × 7. It can then be seen that 2 × 2 × 3 = * and hence the value of * is 12.
Solution © UK Mathematics Trust, from the GK 2018 solutions.