Chickens & Rabbits

Suppose all are chickens; each swap to a rabbit adds 2 legs — keep swapping until the legs match

Medium

Practice Overview

Description: The classic chickens-and-rabbits puzzle: first assume every head is a chicken and count the legs — not enough! Swap chickens into rabbits one by one, each swap adding 2 legs, until the total matches. A step-by-step walk-through of the guess-and-check method.
Estimated Time: 15min
Tags: chickens and rabbitsguess and checkmath puzzlereasoning
Access Level: Free

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About This Practice

There are chickens and rabbits in a cage: 6 heads and 20 legs. How many of each? Guess-and-check says: suppose all 6 are chickens — that's only 12 legs, 8 short. Each chicken swapped into a rabbit adds 2 legs, so swap 8÷2 = 4 of them. Now the legs match exactly: 4 rabbits and 2 chickens.

The classic chickens-and-rabbits puzzle: first assume every head is a chicken and count the legs — not enough! Swap chickens into rabbits one by one, each swap adding 2 legs, until the total matches. A step-by-step walk-through of the guess-and-check method.

MediumEstimated Time: 15minchickens and rabbitsguess and checkmath puzzlereasoning

How to Play

Read the problem: how many heads, how many legs?
Before swapping, think: if all were chickens, how many legs?
Look at the shortage: each swap adds exactly 2 legs.
Keep swapping until the legs match, then count the swaps.
Verify 2×chickens + 4×rabbits, then tap “New One” to practice again.

Learning Objectives

Understand the guess-and-check setup: assume all chickens first.
Use the correspondence “each swap adds 2 legs” to find the answer.
Solve and verify chickens-and-rabbits problems with a number sentence.

Related Themes for This Grade

Chickens & Rabbits - Math Ponderings