Computer - Number Conversion


There are many methods or techniques which can be used to convert numbers from one base to another. In this chapter, we'll demonstrate the following −

  • Decimal to Other Base System
  • Other Base System to Decimal
  • Other Base System to Non-Decimal
  • Shortcut method - Binary to Octal
  • Shortcut method - Octal to Binary
  • Shortcut method - Binary to Hexadecimal
  • Shortcut method - Hexadecimal to Binary

Decimal to Other Base System

Step 1 − Divide the decimal number to be converted by the value of the new base.

Step 2 − Get the remainder from Step 1 as the rightmost digit (least significant digit) of the new base number.

Step 3 − Divide the quotient of the previous divide by the new base.

Step 4 − Record the remainder from Step 3 as the next digit (to the left) of the new base number.

Repeat Steps 3 and 4, getting remainders from right to left, until the quotient becomes zero in Step 3.

The last remainder thus obtained will be the Most Significant Digit (MSD) of the new base number.

Example

Decimal Number: 2910

Calculating Binary Equivalent −

Step Operation Result Remainder
Step 1 29 / 2 14 1
Step 2 14 / 2 7 0
Step 3 7 / 2 3 1
Step 4 3 / 2 1 1
Step 5 1 / 2 0 1

As mentioned in Steps 2 and 4, the remainders have to be arranged in the reverse order so that the first remainder becomes the Least Significant Digit (LSD) and the last remainder becomes the Most Significant Digit (MSD).

Decimal Number : 2910 = Binary Number : 111012.

Other Base System to Decimal System

Step 1 − Determine the column (positional) value of each digit (this depends on the position of the digit and the base of the number system).

Step 2 − Multiply the obtained column values (in Step 1) by the digits in the corresponding columns.

Step 3 − Sum the products calculated in Step 2. The total is the equivalent value in decimal.

Example

Binary Number: 111012

Calculating Decimal Equivalent −

Step Binary Number Decimal Number
Step 1 111012 ((1 x 24) + (1 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10
Step 2 111012 (16 + 8 + 4 + 0 + 1)10
Step 3 111012 2910

Binary Number : 111012 = Decimal Number : 2910

Other Base System to Non-Decimal System

Step 1 − Convert the original number to a decimal number (base 10).

Step 2 − Convert the decimal number so obtained to the new base number.

Example

Octal Number : 258

Calculating Binary Equivalent −

Step 1 - Convert to Decimal

Step Octal Number Decimal Number
Step 1 258 ((2 x 81) + (5 x 80))10
Step 2 258 (16 + 5)10
Step 3 258 2110

Octal Number : 258 = Decimal Number : 2110

Step 2 - Convert Decimal to Binary

Step Operation Result Remainder
Step 1 21 / 2 10 1
Step 2 10 / 2 5 0
Step 3 5 / 2 2 1
Step 4 2 / 2 1 0
Step 5 1 / 2 0 1

Decimal Number : 2110 = Binary Number : 101012

Octal Number : 258 = Binary Number : 101012

Shortcut Method ─ Binary to Octal

Step 1 − Divide the binary digits into groups of three (starting from the right).

Step 2 − Convert each group of three binary digits to one octal digit.

Example

Binary Number : 101012

Calculating Octal Equivalent −

Step Binary Number Octal Number
Step 1 101012 010 101
Step 2 101012 28 58
Step 3 101012 258

Binary Number : 101012 = Octal Number : 258

Shortcut Method ─ Octal to Binary

Step 1 − Convert each octal digit to a 3-digit binary number (the octal digits may be treated as decimal for this conversion).

Step 2 − Combine all the resulting binary groups (of 3 digits each) into a single binary number.

Example

Octal Number : 258

Calculating Binary Equivalent −

Step Octal Number Binary Number
Step 1 258 210 510
Step 2 258 0102 1012
Step 3 258 0101012

Octal Number : 258 = Binary Number : 101012

Shortcut Method ─ Binary to Hexadecimal

Step 1 − Divide the binary digits into groups of four (starting from the right).

Step 2 − Convert each group of four binary digits to one hexadecimal symbol.

Example

Binary Number : 101012

Calculating hexadecimal Equivalent −

Step Binary Number Hexadecimal Number
Step 1 101012 0001 0101
Step 2 101012 110 510
Step 3 101012 1516

Binary Number : 101012 = Hexadecimal Number : 1516

Shortcut Method - Hexadecimal to Binary

Step 1 − Convert each hexadecimal digit to a 4-digit binary number (the hexadecimal digits may be treated as decimal for this conversion).

Step 2 − Combine all the resulting binary groups (of 4 digits each) into a single binary number.

Example

Hexadecimal Number : 1516

Calculating Binary Equivalent −

Step Hexadecimal Number Binary Number
Step 1 1516 110 510
Step 2 1516 00012 01012
Step 3 1516 000101012

Hexadecimal Number : 1516 = Binary Number : 101012

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