1.8 Toothpick Digits - NCERT class 7 maths Textbook - Ganita Prakash
1.8 Toothpick Digits
“Screen Readable NCERT Class 7 Mathematics Textbook - Ganita Prakash - for Blind and Visually Impaired Students prepared by Professor T K Bansal.”
Do you know that We can write digits as shown in the image below:
Figure 1.22
Start of a blue box:
Note by Dr T K Bansal:
I am sure that being a blind person, you are unable to understand the above diagram.Don't worry, I would make you understand the same using indivisually created tables.
1.8.1 Introduction to the Seven-Segment Display
What is a Seven-Segment Display?**
A seven-segment display is a simple electronic device used to show numbers, one digit at a time. You can find it in devices like digital clocks, calculators, microwave ovens, and scoreboards.
Even though it is normally seen visually, the way it works can be understood easily through touch and sound. In this short introduction, you will learn how the 7-segment display is built and how it shows each number.
Structure of a Seven-Segment Display
The display is made up of seven individual bars, called segments. Out of these 7 segments, 3 are horizontal, and 4 are vertical. These segments are arranged in the shape of the number 8. By turning on certain segments and turning off others, the display can form any digit from 0 to 9.
Each of the seven segments has a name. They are labeled with the letters A through G. Think of them like building blocks that can be turned on or off to create different numbers.
Here’s how the segments are arranged:
* Segment A: the top horizontal segment, represented by -
* Segment B: the top right vertical segment, represented by |
* Segment C: the bottom right vertical segment, represented by |
* Segment D: the bottom horizontal segment, represented by -
* Segment E: the bottom left vertical segment, represented by |
* Segment F: the top left vertical segment, represented by |, and
* Segment G: the middle horizontal segment, represented by -.
To give you a clear understanding of the spacial placement of these 7 segment, I have created a 3×5 table. This table has 3 columns, and 5 rows. As you will see in the following table, the 3 horizontal segments are placed one each in the middle column, in rows 1, 3, and 5; whereas, the 4 verticle seglments are placed one each in first and third columns, in rows 2 and 4.
Table: An empty table with 3 columns and 5 rows, that represents the space without any segments.
Table: representation of the placement of the 7 segments in a 7-segment display, represented in a 3×5 table.
| -A | ||
| |F | |B | |
| -G | ||
| |E | |C | |
| -D |
If all the LED's ((Light Emitting Diodes) in the above table are swwitched on, then the 7-segment display reads number 8.
Let us now try to understand how the 7-segment displays the other numerals from 0 through 9.
Numeral 0: Segments A, B, C, D, E, and F are swithced on, whereas, Segment G is kept off. As shown in the following table.
| -A | ||
| |F | |B | |
| |E | |C | |
| -D |
Likewise, the other numerals can be made. For example,<
Numeral 1: Segments B and C are kept on.
Numeral 2: Segments A, B, G, E, and D are switched on.
Numeral 3: Segments A, B, G, C, and D are kept on.
Numeral 4: Segments F, B, G, and C are on.
Numeral 5: Segments A, F, G, C, and D are kept on.
Numeral 6: Segments A, C, D, E, F, and G are on, whereas, only Segment B is off.
Numeral 7: Segments A, B, and C are on.
Numeral 9: All the segments except Segment E are on.
Using a tactile model or a raised diagram, you can feel the position of each segment and learn where they are placed.
End of the blue box.
You can either use toothpicks or matchsticks, or just write the digits in this way, using lines to represent sticks.
To make the digit 7, three sticks are needed.
Question 1.
Write or make the number 5108. How many sticks are required?
(a) Make or write the number 42019. It would require exactly 23 sticks.
(b) Starting with 42019, add or write two more sticks, and make a bigger number. One example is 42,078. What other numbers bigger than 42019 can you make in this way?
(c) Preetham wants to insert the digit ‘1’ somewhere among the digits 4, 2, 0, 1 and 9. Where should he place the digit 1 to get the biggest possible number?
(d) What other numbers can he make by placing the digit 1?
Question 2.
(a) Make or write the number 63890.
(b) Starting with 63890, rearrange exactly four sticks and make a bigger number. One example is 88,078. What other numbers bigger than 63890 can you make in this way?
Make your own questions and challenge each other.
End of Chapter 1.