A student is learning about different number systems used in computing. Number system Base Digits used Binary Denary (decimal) Hexadecimal (a) Complete the ...

Assessment: Computer Science (9-1) 0984 | Paper 1 Mock 01 | Computer Systems Subject: Computer Science (9-1) - 0984

Question 1 Report

A student is learning about different number systems used in computing.

Number systemBaseDigits used
Binary
Denary (decimal)
Hexadecimal

(a) Complete the table. [3]

(b) Convert the denary number 157 into binary. Show your working. [2]

(c) Convert the binary number 11010110 into hexadecimal. Show your working. [1]

Answer Details

(a) The three number systems commonly used in computing are:

Number systemBaseDigits used
BinaryBase 20 and 1 [1]
Denary (decimal)Base 100 to 9 [1]
HexadecimalBase 160 to 9 and A to F [1]

Binary uses only two digits because computer hardware operates on two electrical states (on/off). Denary is the everyday human counting system. Hexadecimal is a shorthand for binary: each hex digit maps to exactly four binary bits, making long binary strings easier to read.

(b) Converting 157 to binary using the place-value method:

1286432168421
10011101

157 = 128 + 16 + 8 + 4 + 1, so the binary representation is 10011101. [2]

(c) Converting 11010110 to hexadecimal:

Split the 8-bit binary number into two groups of 4 bits:

  • 1101 = 8 + 4 + 0 + 1 = 13 = D
  • 0110 = 0 + 4 + 2 + 0 = 6 = 6

Therefore 11010110 in hexadecimal is D6. [1]

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