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Problem 446

Combinatorics Difficulty 2.7 Multiple choice CEMC Gauss (Grade 8) · Canada · 2025

In the diagram, each letter from AA to HH is equal to a different integer from
11 to 88.

Also,

HH is a perfect square and is
11 more than DD
55 and 88 are in the same row
CC is a multiple of both
GG and DD
BB is the largest prime
number in the set
The value of B+GB+G is
even

What is the value of FF?

Pick one

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Official solution

HH is a perfect square and is
11 more than DD.

The perfect squares from 11 to 88 inclusive are 11 and 44. Since HH is one more than DD, HH
cannot be equal to 11 (since D0D\neq0), and so H=4H=4 and D=3D=3.

BB is the largest prime number in
the set, and so B=7B=7.

CC is a multiple of both GG and DD. Since D=3D=3, then C=6C=6 and GG is equal to either 11 or 22 (since 66 is a multiple of each of these).

The value of B+GB+G is even, and since
B=7B=7, then G=1G=1.

The letters which have not been assigned values are AA, EE
and FF, and the integers which have
not been assigned are 22, 55 and 88.

Since 55 and 88 are in the same row and AA and EE are the two remaining unassigned
letters that are in the same row, then AA and EE are 55 and 88 in some order, which leaves F=2F=2.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.