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2021 Beaver Computing Challenge
(Grade 7 & 8)

Questions

Part A

Butterflies

Story

A beaver is photographing butterflies, but after each photo is taken, half the butterflies fly away.

The first photo has 64 butterflies in it and the last photo has 2 butterflies in it.

Question

How many photos did the beaver take?

  1. 6
  2. 63
  3. 4
  4. 32

Overlapping Coins

Story

Emil has six different coins.

Emil placed the six coins on a table, one at a time. Some coins were placed on top of other coins so that they overlap as shown.

Coins A, B, C, D, E, and F are placed in a pile in three levels. Coin D is on the bottom level. Coins C and F are on top of Coin D in the middle level, with Coin C on top of Coin F. Coins A, B and E are on the top level, with coin E on top of Coin B and Coin A on top of Coin E.

Question

Which coin was the fourth coin that Emil placed on the table?

  1. Coin A
  2. Coin B
  3. Coin C
  4. Coin D

Arranging Objects

Story

A board is divided into squares and a different object is placed in each square as shown.

A three by three grid. From left to right, the squares in the first row have the earth, a tree, and an apple, the second row has a flower, a mushroom, and a star, and the third row has the sun, a ladybug, and a clover.

A swap exchanges the locations of two objects. Three swaps occur in this order:

  1. The flower swaps with the tree.
  2. The tree swaps with the ladybug.
  3. The ladybug swaps with the star.

Question

What is the location of the star after the last swap?


  1. First square in the second row.

  2. Third square in the second row.

  3. Second square in the first row.

  4. Second square in the third row.

Genetic Data

Story

A genetic scientist is conducting experiments. Each experiment involves a condition followed by a sequence of letters. The condition includes two numbers and a target letter. An experiment is flagged if the number of times the target letter appears in the sequence is between the two numbers (inclusive).

Example 1

The condition has the numbers 1 and 2, and the target letter A. The sequence of letters is A T G C.

This experiment is flagged because the number of times the target letter A appears in the sequence ATGC is 1 which is between 1 and 2 (inclusive).

Example 2

The condition has the numbers 3 and 8, and the target letter T. The sequence of letters is A T G T.

This experiment is not flagged because the number of times the target letter T appears in the sequence ATGT is 2 which is not between 3 and 8 (inclusive).

Question

How many of the following four experiments will be flagged?

A description of the four experiments follows.

  1. 1
  2. 2
  3. 3
  4. 4

Volcanoes

Story

In the map shown, Dino can follow roads and can climb up and over volcanoes unless they are erupting.

A description of the map follows.

Because two volcanoes are erupting, Dino cannot get from point \(P\) to point \(Q\).

Question

Which two volcanoes are erupting?

  1. Volcanoes 1 and 2
  2. Volcanoes 3 and 4
  3. Volcanoes 1 and 4
  4. Volcanoes 2 and 4

Part B

Forest Towers

Story

In a forest, there are seven towers and eight paths. Each path connects two towers as shown.