I would assume you are working this by hand. If you were on a Windows PC, you could open the Calculator app, change it to programming mode, and manipulate the binary data directly to see the decimal result. To do this by hand, I will explain below.
Convert from binary to decimal:
When converting from Binary to Decimal, each place value has twice the "significance" of the preceding digit. So the far right digit would be worth 1, and the one on the left would be worth 32768. Then you just multiply that number times the binary value at that point(eg 1 or 0)An easy way to do this is to do the following:(the 1* and 0* come from the spec. binary number)
1*(2^15 )+1*(2^14)+0*(2^13)+1*(2^12)+1*(2^11)+0*(2^10)+0*(2^9)+0*(2^8)+0*(2^7)+1*(2^6)+0*(2^5)+1*(2^4)+1*(2^3)+1*(2^2)+0*(2^1)+1*(2^0) = answer(55389)
To convert Decimal to Binary:
This is probably not the most efficient way, but I look at the value and find the closest smaller value that is an exponent of 2 (eg 2^x). In the example 515, the closest lower value would be 512, which is equivalent to (2^9), which means that the ninth bit is set. So far the answer is 1000000000. We are left with 3, since 515 - 512=3. Closest lower value is 2, so the second bit is set. 1000000010. 3-2=1, so we are left with one, which means that the final bit is set. 1000000011. Edit question, and I can help you more if you need it.