How many dominos will be in the set?

Question

A domino set contains all number pair from double zero to double six, with each number pair occurring exactly once. Four example, the domino shown is three-four and also the four-three.
How many dominos will be in the set?

a. 36
b. 31
c. 42
d. 28

Answer 1

Student Question:

A domino set contains all number pair from double zero to double six, with each number pair occurring exactly once. Four example, the domino shown is three-four and also the four-three.

How many dominos will be in the set?

a. 36

b. 31

c. 42

d. 28

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How to solve: (Use Step by Step Approach)

1. Count the number of dominoes from double-zero to double-six
2. Each number pair occurs exactly once

Step 1: Count the Doubles

There are 7 doubles: 0-0,1-1, 2-2, 3-3, 4-4, 5-5, and 6-6

Step 2: Count the non-doubles

6 x 7 divided by 2 = 42/2 = 21

Step 3: Calculate the total number of dominoes

Total number of dominoes: 7 doubles + 21 non-doubles = 28 dominoes

Solution:

There are 28 dominoes in the set

I hope this information is useful. Please let me know if you require any more assistance. If anyone in my neighborhood is interested in setting up an in-person math tutoring session. I look forward to hearing from them. Have an amazing day. Doris H. 5/05/2025