Maths Olympiad Prep

Library / CEMC Fermat /339 of 566

CEMC Fermat

Algebra Difficulty 2.3 Junior Find the answer

If ⊙\odot and ∇\nabla represent different positive integers less than 20, and ⊙×⊙×⊙=∇\odot \times \odot \times \odot = \nabla, what is the value of ∇×∇\nabla \times \nabla?

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Solution

If ⊙=2\odot = 2, then ∇=⊙×⊙×⊙=2×2×2=8\nabla = \odot \times \odot \times \odot = 2 \times 2 \times 2 = 8, which is possible. Thus, ⊙=2\odot = 2 and so ∇=8\nabla = 8. This means that ∇×∇=8×8=64\nabla \times \nabla = 8 \times 8 = 64.

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: Omni-MATH, licensed Apache-2.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.