# LOGIC GATES and logic circuits in a calculator

i am tasked to do a circuit using logic gates regarding the work of a calculator. it is said that how can we make number 3 shown in a calculator represented by logic gates. can someone help me?

i need to light the sections that will form the number 3.

like this image.

• Welcome to EE.SE!. It depends on where do you want to display the number. A 7-segmented display, LCD.. ? – nidhin Aug 24 '18 at 5:20
• Welcome to the site. Please realise that this is not a free design house, homework-answering service or an on-line technical encyclopedia, copied out to you on demand. People will help you take the next step if your question shows that you've done as much as you possibly could on your own - which your post doesn't, I'm afraid. Please revise your question showing your work and findings so far, in considerable detail. Again, a warm welcome to the site. – Oldfart Aug 24 '18 at 6:27
• @Jessa, you wouldn't need any gates just to show a '3' on a calculator. You could wire up the display to permanently show a '3'. There must be more to the question. For example, "Using gates show how to calculate and display the sum of two 3-bit binary numbers". – Transistor Aug 24 '18 at 6:40
• hi, i added a pic, thought it might help elaborate my problem. – Jessa Buan Aug 24 '18 at 8:06
• actually, this topic was not discussed to us thoroughly so I am not familiar with the terms, sorry. – Jessa Buan Aug 24 '18 at 8:08

Since this seems to be homework we won't give you a full answer but will guide you through.

1. Name the segments on your seven-segment display.

Figure 1. Standard segment naming. Image source: 7-segment display basics.

1. Next create a table to show what segments are required by each digit. e.g.

Table 1. 7-segment decoder.

         Binary     Segment
Decimal  d c b a    A B C D E F G
0  0 0 0 0    1 1 1 1 1 1 0
1  0 0 0 1    0 1 1 0 0 0 0
2  0 0 1 0    ....

1. Write the equations for each segment.

2. Draw the logic diagram.

• I've reorganised Table 1 to make it a little easier to work with. Copy it into your question and finish all the rows then you should be able to proceed to the next step. Ping me with @transistor to let me know when you're ready. – Transistor Aug 24 '18 at 13:49