What is 00001010.01100100.00000111.00010101 to decimal?

Answer 1

It's quite easy to convert binary into hexadecimal (hex) by grouping each 4 binary digits (bits) into a single binary hex digit:

0A 64 07 15

From there it's easier to convert into decimal in the head:

10 100 7 21

If you will be doing much in the way of programming computers, or working with TCP/IP networking, it is definitely a good idea to spend some time familiarising yourself with hexadecimal and converting between hex, binary and decimal.

For reference, converting from binary to hex is done like this:

0000 = 0

0001 = 1

0010 = 2

0011 = 3

0100 = 4

0101 = 5

0110 = 6

0111 = 7

1000 = 8

1001 = 9

1010 = A

1011 = B

1100 = C

1101 = D

1110 = E

1111 = F

Answer 2

The value 01000001, which happens to be octal because of the leading zero, is 1000000000000000001 in binary.

Answer 3

Same as 1. Unless you also have a decimal point somewhere (which you didn't include in the question).

Answer 4

0x1

You can drop leading 0's.