A car has many embedded systems - Edexcel - GCSE Computer Science - Question 2 - 2018 - Paper 1

To convert the binary number 0010 0011 to denary, we assign powers of 2 to each bit:

• The binary number can be expressed as: $0 \times 2^7 + 0 \times 2^6 + 1 \times 2^5 + 0 \times 2^4 + 0 \times 2^3 + 1 \times 2^2 + 1 \times 2^1 + 1 \times 2^0$

• Calculating this gives: $1 \times 32 + 0 + 0 + 1 \times 4 + 1 \times 2 + 1 \times 1 = 32 + 4 + 2 + 1 = 35$

Therefore, the denary representation of the binary number 0010 0011 is: 35.

To add the binary numbers 0010 0011 and 0100 1010, we align them and add like in decimal:

   0010 0011
 + 0100 1010
 -----------
   0110 1101

Thus, the result of adding 0010 0011 and 0100 1010 in binary is: 0110 1101.

One reason why encryption is used is to keep data secure. This ensures that sensitive information cannot be accessed by unauthorized users.

To apply a Caesar Cipher with a shift of +4:

1. The letter 'b' shifts to 'f'.
2. The letter 'r' shifts to 'v'.
3. The letter 'a' shifts to 'e'.
4. The letter 'k' shifts to 'o'.
5. The letter 'e' shifts to 'i'.
6. The letter 's' shifts to 'w'.

Thus, the cipher text for 'brakes' is 'fveoiw'.

A special condition a Caesar Cipher must handle is the wrap-around of letters at the end of the alphabet. For example, if the shifting moves past 'z', it should wrap around to 'a'. For instance, shifting 'z' by +4 will yield 'd'.