MyCERT 3rd Quarter 2011 Summary Report - CyberSAFE Malaysia

compare the difference between a binarynumber and a decimal number. For instance,look at number “9”. When number “9” isadded with “1”, it will become “10” whichis a two digit number. The number of digitsincreases each time a single digit numberis exhausted. Single digit numbers can berotated from “0” until “9”. When number “9”is reached, it only can return to “0” by addingone extra digit on its left.In a decimal number system, single digitnumbers can be rotated from zero untilnine meanwhile for binary number systems,single digit numbers can only rotate fromzero to one. If the number, x is larger than“1”, find the highest degree n where x-2n> 0. Repeat the above method until theremainder is less than “2”. If the remainderis less than “2”, the remainder representsthe value in the last column.Mathematics OperationBinary AdditionThe basic concept in binary number additionoperation is almost the same as decimalnumbers. The difference between thesenumber systems is that decimal numbersuse digits “0” to “9” while binary numbersuse digits “0” and “1”. If the value of twoadditional numbers is larger than “1”, itshould be carried a column to the left. Belowis an example on binary additional operationfor single-bit binary numbers.0 + 0 = 00 + 1 = 11 + 0 = 11 + 1 = 0 , carry 129How To Convert Binary IntoDecimal?Binary numbers are actually summation ofbase two powers. Digit in the right most ofa binary number represents 20. Left mostdigit of a binary number is the highestvalue. The power increases by one foreach digit on the left. To convert a binarynumber into a decimal number, each digitneed to be multiplied by base two powernumber and the power is dependent on theposition of each digit in the binary number.The power starts from the right which is 20and increase by one power as it goes to theleft. If the binary number contains six digits,the highest value would be 25. Refer to theexample below for a better understandingon how to convert binary strings intodecimal numbers.Let’s calculate “1+1” in decimal, “2” is theanswer. Since “2” is larger than “1” (where“1” is the maximum digit in binary), “1” hasto be carried a column to the left and “0”(In decimal, “2” minus “2” is equal to “0”)is the remainder. So “1+1” is equal to “10”in binary number. The process is the samefor multiple-bit binary numbers. Here is anexample on additional operation of multiplebitbinary numbers.111 (carried digit)10011+ 1110= 100001i) Binary ii) Decimal1 (carried digit)19+ 14= 33101011 = (1 x 25) + (0 x 24) + (1 x 23) + (0 x 22) +(1 x 21) + (1 x 20)= (1 x 32) + (0 x 16) + (1 x 8) + (0 x 4) + (1 x 2) +(1 x 1)= 32 + 0 + 8 + 0 + 0 + 2 + 1= 43Binary SubtractionBinary subtraction operates almost the sameas decimal numbers. Both number systemsuse the same “borrow” method. If a columnvalue is smaller than the value that we wante-Security | Cyber Security Malaysia | Vol: 28-(Q3/2011)© CyberSecurity Malaysia 2011 - All Rights Reserved