1.100 120 999 991 8 Converted to 64 Bit Double Precision IEEE 754 Binary Floating Point Representation Standard

Convert decimal 1.100 120 999 991 8(10) to 64 bit double precision IEEE 754 binary floating point representation standard (1 bit for sign, 11 bits for exponent, 52 bits for mantissa)

What are the steps to convert decimal number
1.100 120 999 991 8(10) to 64 bit double precision IEEE 754 binary floating point representation (1 bit for sign, 11 bits for exponent, 52 bits for mantissa)

1. First, convert to binary (in base 2) the integer part: 1.
Divide the number repeatedly by 2.

Keep track of each remainder.

We stop when we get a quotient that is equal to zero.


  • division = quotient + remainder;
  • 1 ÷ 2 = 0 + 1;

2. Construct the base 2 representation of the integer part of the number.

Take all the remainders starting from the bottom of the list constructed above.

1(10) =

1(2)


3. Convert to binary (base 2) the fractional part: 0.100 120 999 991 8.

Multiply it repeatedly by 2.

Keep track of each integer part of the results.

Stop when we get a fractional part that is equal to zero.


  • #) multiplying = integer + fractional part;
  • 1) 0.100 120 999 991 8 × 2 = 0 + 0.200 241 999 983 6;
  • 2) 0.200 241 999 983 6 × 2 = 0 + 0.400 483 999 967 2;
  • 3) 0.400 483 999 967 2 × 2 = 0 + 0.800 967 999 934 4;
  • 4) 0.800 967 999 934 4 × 2 = 1 + 0.601 935 999 868 8;
  • 5) 0.601 935 999 868 8 × 2 = 1 + 0.203 871 999 737 6;
  • 6) 0.203 871 999 737 6 × 2 = 0 + 0.407 743 999 475 2;
  • 7) 0.407 743 999 475 2 × 2 = 0 + 0.815 487 998 950 4;
  • 8) 0.815 487 998 950 4 × 2 = 1 + 0.630 975 997 900 8;
  • 9) 0.630 975 997 900 8 × 2 = 1 + 0.261 951 995 801 6;
  • 10) 0.261 951 995 801 6 × 2 = 0 + 0.523 903 991 603 2;
  • 11) 0.523 903 991 603 2 × 2 = 1 + 0.047 807 983 206 4;
  • 12) 0.047 807 983 206 4 × 2 = 0 + 0.095 615 966 412 8;
  • 13) 0.095 615 966 412 8 × 2 = 0 + 0.191 231 932 825 6;
  • 14) 0.191 231 932 825 6 × 2 = 0 + 0.382 463 865 651 2;
  • 15) 0.382 463 865 651 2 × 2 = 0 + 0.764 927 731 302 4;
  • 16) 0.764 927 731 302 4 × 2 = 1 + 0.529 855 462 604 8;
  • 17) 0.529 855 462 604 8 × 2 = 1 + 0.059 710 925 209 6;
  • 18) 0.059 710 925 209 6 × 2 = 0 + 0.119 421 850 419 2;
  • 19) 0.119 421 850 419 2 × 2 = 0 + 0.238 843 700 838 4;
  • 20) 0.238 843 700 838 4 × 2 = 0 + 0.477 687 401 676 8;
  • 21) 0.477 687 401 676 8 × 2 = 0 + 0.955 374 803 353 6;
  • 22) 0.955 374 803 353 6 × 2 = 1 + 0.910 749 606 707 2;
  • 23) 0.910 749 606 707 2 × 2 = 1 + 0.821 499 213 414 4;
  • 24) 0.821 499 213 414 4 × 2 = 1 + 0.642 998 426 828 8;
  • 25) 0.642 998 426 828 8 × 2 = 1 + 0.285 996 853 657 6;
  • 26) 0.285 996 853 657 6 × 2 = 0 + 0.571 993 707 315 2;
  • 27) 0.571 993 707 315 2 × 2 = 1 + 0.143 987 414 630 4;
  • 28) 0.143 987 414 630 4 × 2 = 0 + 0.287 974 829 260 8;
  • 29) 0.287 974 829 260 8 × 2 = 0 + 0.575 949 658 521 6;
  • 30) 0.575 949 658 521 6 × 2 = 1 + 0.151 899 317 043 2;
  • 31) 0.151 899 317 043 2 × 2 = 0 + 0.303 798 634 086 4;
  • 32) 0.303 798 634 086 4 × 2 = 0 + 0.607 597 268 172 8;
  • 33) 0.607 597 268 172 8 × 2 = 1 + 0.215 194 536 345 6;
  • 34) 0.215 194 536 345 6 × 2 = 0 + 0.430 389 072 691 2;
  • 35) 0.430 389 072 691 2 × 2 = 0 + 0.860 778 145 382 4;
  • 36) 0.860 778 145 382 4 × 2 = 1 + 0.721 556 290 764 8;
  • 37) 0.721 556 290 764 8 × 2 = 1 + 0.443 112 581 529 6;
  • 38) 0.443 112 581 529 6 × 2 = 0 + 0.886 225 163 059 2;
  • 39) 0.886 225 163 059 2 × 2 = 1 + 0.772 450 326 118 4;
  • 40) 0.772 450 326 118 4 × 2 = 1 + 0.544 900 652 236 8;
  • 41) 0.544 900 652 236 8 × 2 = 1 + 0.089 801 304 473 6;
  • 42) 0.089 801 304 473 6 × 2 = 0 + 0.179 602 608 947 2;
  • 43) 0.179 602 608 947 2 × 2 = 0 + 0.359 205 217 894 4;
  • 44) 0.359 205 217 894 4 × 2 = 0 + 0.718 410 435 788 8;
  • 45) 0.718 410 435 788 8 × 2 = 1 + 0.436 820 871 577 6;
  • 46) 0.436 820 871 577 6 × 2 = 0 + 0.873 641 743 155 2;
  • 47) 0.873 641 743 155 2 × 2 = 1 + 0.747 283 486 310 4;
  • 48) 0.747 283 486 310 4 × 2 = 1 + 0.494 566 972 620 8;
  • 49) 0.494 566 972 620 8 × 2 = 0 + 0.989 133 945 241 6;
  • 50) 0.989 133 945 241 6 × 2 = 1 + 0.978 267 890 483 2;
  • 51) 0.978 267 890 483 2 × 2 = 1 + 0.956 535 780 966 4;
  • 52) 0.956 535 780 966 4 × 2 = 1 + 0.913 071 561 932 8;
  • 53) 0.913 071 561 932 8 × 2 = 1 + 0.826 143 123 865 6;

We didn't get any fractional part that was equal to zero. But we had enough iterations (over Mantissa limit) and at least one integer that was different from zero => FULL STOP (Losing precision - the converted number we get in the end will be just a very good approximation of the initial one).


4. Construct the base 2 representation of the fractional part of the number.

Take all the integer parts of the multiplying operations, starting from the top of the constructed list above:


0.100 120 999 991 8(10) =

0.0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111 1(2)

5. Positive number before normalization:

1.100 120 999 991 8(10) =

1.0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111 1(2)

6. Normalize the binary representation of the number.

Shift the decimal mark 0 positions to the left, so that only one non zero digit remains to the left of it:


1.100 120 999 991 8(10) =

1.0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111 1(2) =

1.0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111 1(2) × 20


7. Up to this moment, there are the following elements that would feed into the 64 bit double precision IEEE 754 binary floating point representation:

Sign 0 (a positive number)

Exponent (unadjusted): 0

Mantissa (not normalized):
1.0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111 1


8. Adjust the exponent.

Use the 11 bit excess/bias notation:


Exponent (adjusted) =

Exponent (unadjusted) + 2(11-1) - 1 =

0 + 2(11-1) - 1 =

(0 + 1 023)(10) =

1 023(10)


9. Convert the adjusted exponent from the decimal (base 10) to 11 bit binary.

Use the same technique of repeatedly dividing by 2:


  • division = quotient + remainder;
  • 1 023 ÷ 2 = 511 + 1;
  • 511 ÷ 2 = 255 + 1;
  • 255 ÷ 2 = 127 + 1;
  • 127 ÷ 2 = 63 + 1;
  • 63 ÷ 2 = 31 + 1;
  • 31 ÷ 2 = 15 + 1;
  • 15 ÷ 2 = 7 + 1;
  • 7 ÷ 2 = 3 + 1;
  • 3 ÷ 2 = 1 + 1;
  • 1 ÷ 2 = 0 + 1;

10. Construct the base 2 representation of the adjusted exponent.

Take all the remainders starting from the bottom of the list constructed above.


Exponent (adjusted) =

1023(10) =

011 1111 1111(2)


11. Normalize the mantissa.

a) Remove the leading (the leftmost) bit, since it's allways 1, and the decimal point, if the case.

b) Adjust its length to 52 bits, by removing the excess bits, from the right (if any of the excess bits is set on 1, we are losing precision...).


Mantissa (normalized) =

1. 0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111 1 =

0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111


12. The three elements that make up the number's 64 bit double precision IEEE 754 binary floating point representation:

Sign (1 bit) =
0 (a positive number)

Exponent (11 bits) =
011 1111 1111

Mantissa (52 bits) =
0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111


Decimal number 1.100 120 999 991 8 converted to 64 bit double precision IEEE 754 binary floating point representation:

0 - 011 1111 1111 - 0001 1001 1010 0001 1000 0111 1010 0100 1001 1011 1000 1011 0111

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How to convert numbers from the decimal system (base ten) to 64 bit double precision IEEE 754 binary floating point standard

Follow the steps below to convert a base 10 decimal number to 64 bit double precision IEEE 754 binary floating point:

  • 1. If the number to be converted is negative, start with its the positive version.
  • 2. First convert the integer part. Divide repeatedly by 2 the positive representation of the integer number that is to be converted to binary, until we get a quotient that is equal to zero, keeping track of each remainder.
  • 3. Construct the base 2 representation of the positive integer part of the number, by taking all the remainders from the previous operations, starting from the bottom of the list constructed above. Thus, the last remainder of the divisions becomes the first symbol (the leftmost) of the base two number, while the first remainder becomes the last symbol (the rightmost).
  • 4. Then convert the fractional part. Multiply the number repeatedly by 2, until we get a fractional part that is equal to zero, keeping track of each integer part of the results.
  • 5. Construct the base 2 representation of the fractional part of the number, by taking all the integer parts of the multiplying operations, starting from the top of the list constructed above (they should appear in the binary representation, from left to right, in the order they have been calculated).
  • 6. Normalize the binary representation of the number, shifting the decimal mark (the decimal point) "n" positions either to the left, or to the right, so that only one non zero digit remains to the left of the decimal mark.
  • 7. Adjust the exponent in 11 bit excess/bias notation and then convert it from decimal (base 10) to 11 bit binary, by using the same technique of repeatedly dividing by 2, as shown above:
    Exponent (adjusted) = Exponent (unadjusted) + 2(11-1) - 1
  • 8. Normalize mantissa, remove the leading (leftmost) bit, since it's allways '1' (and the decimal mark, if the case) and adjust its length to 52 bits, either by removing the excess bits from the right (losing precision...) or by adding extra bits set on '0' to the right.
  • 9. Sign (it takes 1 bit) is either 1 for a negative or 0 for a positive number.

Example: convert the negative number -31.640 215 from the decimal system (base ten) to 64 bit double precision IEEE 754 binary floating point:

  • 1. Start with the positive version of the number:

    |-31.640 215| = 31.640 215

  • 2. First convert the integer part, 31. Divide it repeatedly by 2, keeping track of each remainder, until we get a quotient that is equal to zero:
    • division = quotient + remainder;
    • 31 ÷ 2 = 15 + 1;
    • 15 ÷ 2 = 7 + 1;
    • 7 ÷ 2 = 3 + 1;
    • 3 ÷ 2 = 1 + 1;
    • 1 ÷ 2 = 0 + 1;
    • We have encountered a quotient that is ZERO => FULL STOP
  • 3. Construct the base 2 representation of the integer part of the number by taking all the remainders of the previous dividing operations, starting from the bottom of the list constructed above:

    31(10) = 1 1111(2)

  • 4. Then, convert the fractional part, 0.640 215. Multiply repeatedly by 2, keeping track of each integer part of the results, until we get a fractional part that is equal to zero:
    • #) multiplying = integer + fractional part;
    • 1) 0.640 215 × 2 = 1 + 0.280 43;
    • 2) 0.280 43 × 2 = 0 + 0.560 86;
    • 3) 0.560 86 × 2 = 1 + 0.121 72;
    • 4) 0.121 72 × 2 = 0 + 0.243 44;
    • 5) 0.243 44 × 2 = 0 + 0.486 88;
    • 6) 0.486 88 × 2 = 0 + 0.973 76;
    • 7) 0.973 76 × 2 = 1 + 0.947 52;
    • 8) 0.947 52 × 2 = 1 + 0.895 04;
    • 9) 0.895 04 × 2 = 1 + 0.790 08;
    • 10) 0.790 08 × 2 = 1 + 0.580 16;
    • 11) 0.580 16 × 2 = 1 + 0.160 32;
    • 12) 0.160 32 × 2 = 0 + 0.320 64;
    • 13) 0.320 64 × 2 = 0 + 0.641 28;
    • 14) 0.641 28 × 2 = 1 + 0.282 56;
    • 15) 0.282 56 × 2 = 0 + 0.565 12;
    • 16) 0.565 12 × 2 = 1 + 0.130 24;
    • 17) 0.130 24 × 2 = 0 + 0.260 48;
    • 18) 0.260 48 × 2 = 0 + 0.520 96;
    • 19) 0.520 96 × 2 = 1 + 0.041 92;
    • 20) 0.041 92 × 2 = 0 + 0.083 84;
    • 21) 0.083 84 × 2 = 0 + 0.167 68;
    • 22) 0.167 68 × 2 = 0 + 0.335 36;
    • 23) 0.335 36 × 2 = 0 + 0.670 72;
    • 24) 0.670 72 × 2 = 1 + 0.341 44;
    • 25) 0.341 44 × 2 = 0 + 0.682 88;
    • 26) 0.682 88 × 2 = 1 + 0.365 76;
    • 27) 0.365 76 × 2 = 0 + 0.731 52;
    • 28) 0.731 52 × 2 = 1 + 0.463 04;
    • 29) 0.463 04 × 2 = 0 + 0.926 08;
    • 30) 0.926 08 × 2 = 1 + 0.852 16;
    • 31) 0.852 16 × 2 = 1 + 0.704 32;
    • 32) 0.704 32 × 2 = 1 + 0.408 64;
    • 33) 0.408 64 × 2 = 0 + 0.817 28;
    • 34) 0.817 28 × 2 = 1 + 0.634 56;
    • 35) 0.634 56 × 2 = 1 + 0.269 12;
    • 36) 0.269 12 × 2 = 0 + 0.538 24;
    • 37) 0.538 24 × 2 = 1 + 0.076 48;
    • 38) 0.076 48 × 2 = 0 + 0.152 96;
    • 39) 0.152 96 × 2 = 0 + 0.305 92;
    • 40) 0.305 92 × 2 = 0 + 0.611 84;
    • 41) 0.611 84 × 2 = 1 + 0.223 68;
    • 42) 0.223 68 × 2 = 0 + 0.447 36;
    • 43) 0.447 36 × 2 = 0 + 0.894 72;
    • 44) 0.894 72 × 2 = 1 + 0.789 44;
    • 45) 0.789 44 × 2 = 1 + 0.578 88;
    • 46) 0.578 88 × 2 = 1 + 0.157 76;
    • 47) 0.157 76 × 2 = 0 + 0.315 52;
    • 48) 0.315 52 × 2 = 0 + 0.631 04;
    • 49) 0.631 04 × 2 = 1 + 0.262 08;
    • 50) 0.262 08 × 2 = 0 + 0.524 16;
    • 51) 0.524 16 × 2 = 1 + 0.048 32;
    • 52) 0.048 32 × 2 = 0 + 0.096 64;
    • 53) 0.096 64 × 2 = 0 + 0.193 28;
    • We didn't get any fractional part that was equal to zero. But we had enough iterations (over Mantissa limit = 52) and at least one integer part that was different from zero => FULL STOP (losing precision...).
  • 5. Construct the base 2 representation of the fractional part of the number, by taking all the integer parts of the previous multiplying operations, starting from the top of the constructed list above:

    0.640 215(10) = 0.1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0(2)

  • 6. Summarizing - the positive number before normalization:

    31.640 215(10) = 1 1111.1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0(2)

  • 7. Normalize the binary representation of the number, shifting the decimal mark 4 positions to the left so that only one non-zero digit stays to the left of the decimal mark:

    31.640 215(10) =
    1 1111.1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0(2) =
    1 1111.1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0(2) × 20 =
    1.1111 1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0(2) × 24

  • 8. Up to this moment, there are the following elements that would feed into the 64 bit double precision IEEE 754 binary floating point representation:

    Sign: 1 (a negative number)

    Exponent (unadjusted): 4

    Mantissa (not-normalized): 1.1111 1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0

  • 9. Adjust the exponent in 11 bit excess/bias notation and then convert it from decimal (base 10) to 11 bit binary (base 2), by using the same technique of repeatedly dividing it by 2, as shown above:

    Exponent (adjusted) = Exponent (unadjusted) + 2(11-1) - 1 = (4 + 1023)(10) = 1027(10) =
    100 0000 0011(2)

  • 10. Normalize mantissa, remove the leading (leftmost) bit, since it's allways '1' (and the decimal sign) and adjust its length to 52 bits, by removing the excess bits, from the right (losing precision...):

    Mantissa (not-normalized): 1.1111 1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100 1010 0

    Mantissa (normalized): 1111 1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100

  • Conclusion:

    Sign (1 bit) = 1 (a negative number)

    Exponent (8 bits) = 100 0000 0011

    Mantissa (52 bits) = 1111 1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100

  • Number -31.640 215, converted from decimal system (base 10) to 64 bit double precision IEEE 754 binary floating point =
    1 - 100 0000 0011 - 1111 1010 0011 1110 0101 0010 0001 0101 0111 0110 1000 1001 1100