Convert 0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011 Base 2 Signed Binary Number on 64 Bit - To Base 10 Decimal System Integer

How to convert 0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011(2), the base 2 signed binary number on 64 bit, to a base 10 decimal system integer

What are the steps to convert the base 2 signed binary number
0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011(2) to a base 10 decimal system equivalent integer?

1. Is this a positive or a negative number?

0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011 is the binary representation of a positive integer, on 64 bits (8 Bytes).


  • In a signed binary, the first bit (the leftmost) is reserved for the sign, 1 = negative, 0 = positive. This bit does not count when calculating the absolute value.

2. Construct the unsigned binary number.

Exclude the first bit (the leftmost), that is reserved for the sign:

0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011 = 101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011


3. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:

  • 262

    1

  • 261

    0

  • 260

    1

  • 259

    0

  • 258

    1

  • 257

    0

  • 256

    1

  • 255

    0

  • 254

    0

  • 253

    1

  • 252

    0

  • 251

    1

  • 250

    0

  • 249

    1

  • 248

    0

  • 247

    1

  • 246

    1

  • 245

    0

  • 244

    0

  • 243

    1

  • 242

    0

  • 241

    1

  • 240

    0

  • 239

    1

  • 238

    0

  • 237

    0

  • 236

    1

  • 235

    0

  • 234

    1

  • 233

    0

  • 232

    1

  • 231

    0

  • 230

    0

  • 229

    0

  • 228

    0

  • 227

    0

  • 226

    1

  • 225

    0

  • 224

    1

  • 223

    0

  • 222

    1

  • 221

    0

  • 220

    0

  • 219

    1

  • 218

    0

  • 217

    1

  • 216

    0

  • 215

    1

  • 214

    0

  • 213

    1

  • 212

    0

  • 211

    1

  • 210

    0

  • 29

    1

  • 28

    0

  • 27

    0

  • 26

    1

  • 25

    0

  • 24

    0

  • 23

    1

  • 22

    0

  • 21

    1

  • 20

    1

4. Multiply each bit by its corresponding power of 2 and add all the terms up.

101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011(2) =

(1 × 262 + 0 × 261 + 1 × 260 + 0 × 259 + 1 × 258 + 0 × 257 + 1 × 256 + 0 × 255 + 0 × 254 + 1 × 253 + 0 × 252 + 1 × 251 + 0 × 250 + 1 × 249 + 0 × 248 + 1 × 247 + 1 × 246 + 0 × 245 + 0 × 244 + 1 × 243 + 0 × 242 + 1 × 241 + 0 × 240 + 1 × 239 + 0 × 238 + 0 × 237 + 1 × 236 + 0 × 235 + 1 × 234 + 0 × 233 + 1 × 232 + 0 × 231 + 0 × 230 + 0 × 229 + 0 × 228 + 0 × 227 + 1 × 226 + 0 × 225 + 1 × 224 + 0 × 223 + 1 × 222 + 0 × 221 + 0 × 220 + 1 × 219 + 0 × 218 + 1 × 217 + 0 × 216 + 1 × 215 + 0 × 214 + 1 × 213 + 0 × 212 + 1 × 211 + 0 × 210 + 1 × 29 + 0 × 28 + 0 × 27 + 1 × 26 + 0 × 25 + 0 × 24 + 1 × 23 + 0 × 22 + 1 × 21 + 1 × 20)(10) =

(4 611 686 018 427 387 904 + 0 + 1 152 921 504 606 846 976 + 0 + 288 230 376 151 711 744 + 0 + 72 057 594 037 927 936 + 0 + 0 + 9 007 199 254 740 992 + 0 + 2 251 799 813 685 248 + 0 + 562 949 953 421 312 + 0 + 140 737 488 355 328 + 70 368 744 177 664 + 0 + 0 + 8 796 093 022 208 + 0 + 2 199 023 255 552 + 0 + 549 755 813 888 + 0 + 0 + 68 719 476 736 + 0 + 17 179 869 184 + 0 + 4 294 967 296 + 0 + 0 + 0 + 0 + 0 + 67 108 864 + 0 + 16 777 216 + 0 + 4 194 304 + 0 + 0 + 524 288 + 0 + 131 072 + 0 + 32 768 + 0 + 8 192 + 0 + 2 048 + 0 + 512 + 0 + 0 + 64 + 0 + 0 + 8 + 0 + 2 + 1)(10) =

(4 611 686 018 427 387 904 + 1 152 921 504 606 846 976 + 288 230 376 151 711 744 + 72 057 594 037 927 936 + 9 007 199 254 740 992 + 2 251 799 813 685 248 + 562 949 953 421 312 + 140 737 488 355 328 + 70 368 744 177 664 + 8 796 093 022 208 + 2 199 023 255 552 + 549 755 813 888 + 68 719 476 736 + 17 179 869 184 + 4 294 967 296 + 67 108 864 + 16 777 216 + 4 194 304 + 524 288 + 131 072 + 32 768 + 8 192 + 2 048 + 512 + 64 + 8 + 2 + 1)(10) =

6 136 940 183 633 439 307(10)

5. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:

0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011(2) = 6 136 940 183 633 439 307(10)

0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011(2), Base 2 signed binary number, converted and written as a base 10 decimal system equivalent integer:
0101 0101 0010 1010 1100 1010 1001 0101 0000 0101 0100 1010 1010 1010 0100 1011(2) = 6 136 940 183 633 439 307(10)

Spaces were used to group digits: for binary, by 4, for decimal, by 3.

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How to convert signed binary numbers from binary system to decimal (base ten)

To understand how to convert a signed binary number from binary system to decimal (base ten), the easiest way is to do it through an example - convert the binary number, 1001 1110, to base ten:

  • In a signed binary, the first bit (leftmost) is reserved for the sign, 1 = negative, 0 = positive. This bit does not count when calculating the absolute value (value without sign). The first bit is 1, so our number is negative.
  • Write bellow the binary number in base two, and above each bit that makes up the binary number write the corresponding power of 2 (numeral base) that its place value represents, starting with zero, from the right of the number (rightmost bit), walking to the left of the number and increasing each corresonding power of 2 by exactly one unit, but ignoring the very first bit (the leftmost, the one representing the sign):
  • powers of 2:   6 5 4 3 2 1 0
    digits: 1 0 0 1 1 1 1 0
  • Build the representation of the positive number in base 10, by taking each digit of the binary number, multiplying it by the corresponding power of 2 and then adding all the terms up, but also taking care of the number sign:

    1001 1110 =

    - (0 × 26 + 0 × 25 + 1 × 24 + 1 × 23 + 1 × 22 + 1 × 21 + 0 × 20)(10) =

    - (0 + 0 + 16 + 8 + 4 + 2 + 0)(10) =

    - (16 + 8 + 4 + 2)(10) =

    -30(10)

  • Binary signed number, 1001 1110 = -30(10), signed negative integer in base 10