One of the other tasks required for GCSE computer science is the ability to add two binary numbers up to 8 bits and consider overflow. But starting small might be better

Hopefully this interactive will help.

Starting Small

In binary 1₂ + 0₂ = 1₂

(The little 2 denotes using binary or base 2)

But look at the next two additions

1₂ + 1₂ = 10₂

1₂ + 1₂ + 1₂ = 11₂

This means that, in column addition, you will need to carry a bit to the next column!

Up to 4 bits

• Make your own numbers by clicking on the digits or set a random question.
• Click on the answer digits on the lower register to set the answer
• Click Check to see if you are correct.
  (You can hide the carry digits if necessary)

Try it first with 4 binary digits (4 bits or a nibble)

Open Full Screen

Making it bigger (8 bit)

Once you have mastered this, then try with a whole byte (8 bits)

Open Full Screen

Further investigation

What happens when the answer exceeds 8 bits?
Investigate this overflow…