Halina’s clock uses a digital LED display where each digit is represented by seven
LED segments that are either on or oﬀ, as shown.
Sometimes some of the LED segments stop working. When the top-
most horizontal LED segment stopped working, both the digit 1 and
the digit 7 appeared as shown. This was a problem because Halina
couldn’t distinguish between them.
Halina replaced the broken LED segment, but then a week later found that a
diﬀerent LED segment had stopped working. However, this time, she was still
able to distinguish between all ten digits.
What is the largest number of LED segments that can be broken at the same
time, while still allowing Halina to distinguish between all ten digits?
This problem was inspired by a past Beaver Computing Challenge (BCC) problem

This problem involves a seven-segment digital display, where each digit (0 through 9) is represented by a combination of seven LED segments, which can be either on or off. To find the largest number of LED segments that can be broken while still allowing all ten digits to be distinguishable, we need to carefully analyze the display patterns and how much flexibility there is with segment failures.

### Step-by-step breakdown:

1. **Understanding the seven-segment display:**
   The seven segments in a typical digital display are labeled as follows:

   ```
    a
   ----
  |    |
 f|    |b
   ----
  |    |
 e|    |c
   ----
    d
   ```

   Each digit from 0 to 9 lights up a certain combination of these seven segments. For example:
   - 0 lights up segments a, b, c, e, f, g.
   - 1 lights up segments b, c.
   - 2 lights up segments a, b, d, e, g.
   - And so on.

2. **Key observation:**
   If too many segments break, certain digits might look the same, which means Halina won't be able to distinguish between them. However, we need to find the maximum number of segments that can break while still allowing every digit (0 through 9) to remain distinguishable from the others.

3. **Distinguishing between all digits:**
   Let's break the problem down by considering different segments failing. For each broken segment, we need to check if all the digits can still be uniquely represented. If a segment breaks but we can still uniquely identify all digits, then we proceed. If it breaks down the ability to distinguish two or more digits, we cannot break that segment.

4. **Strategic segment breakdown:**
   Let's try to remove segments while maintaining distinct representations for each digit:
   
   - **Segment "a":** If this segment fails, digits like 7 and 1 would still be distinguishable (7 has other segments lit). Breaking "a" works.
   - **Segment "d":** Breaking this would leave 0 and 8 distinguishable since other segments like "g" would differentiate them. So, breaking "d" works.
   - **Segment "g":** Breaking this can still differentiate between digits, such as 8 and 0, because other segments like "e" and "c" will help. So, breaking "g" works.

   Now, let's try to break **as many segments** as possible.

5. **Maximum number of segments:**
   After trial and error, it turns out that you can break up to **3 segments** at once while still allowing all 10 digits to be distinguishable.

Thus, the largest number of segments that can be broken while still distinguishing all digits is **3**.

---

Would you like more details or have any questions? Here are five related questions to consider:

1. How does breaking different individual segments affect specific digits?
2. What happens if two adjacent segments are broken?
3. How many segments are required to display just the digit "8"?
4. Can the display be designed in a way to allow more broken segments while keeping digits distinguishable?
5. How can you mathematically determine which segments are the most critical?

**Tip:** When working with seven-segment displays, visualizing how each digit is represented by active segments can help solve complex failure-related problems.

Halina’s clock uses a digital LED display where each digit is represented by seven LED segments that are either on or off, as shown. Sometimes some of the LED segments stop working. When the top-most horizontal LED segment stopped working, both the digit 1 and the digit 7 appeared as shown. This was a problem because Halina couldn’t distinguish between them. Halina replaced the broken LED segment, but then a week later found that a different LED segment had stopped working. However, this time, she was still able to distinguish between all ten digits. What is the largest number of LED segments that can be broken at the same time, while still allowing Halina to distinguish between all ten digits?

Explore how to determine the maximum number of broken segments in a seven-segment digital display while still allowing the digits 0-9 to be distinguishable. This problem involves combinatorics, logic, and pattern recognition, suitable for students in Grades 9-12.

Math Problem Statement

Solution

Ask a new question for Free

By Image

Math Problem Analysis

Mathematical Concepts

Formulas

Theorems

Suitable Grade Level

Related Recommendation