These are Chapter 1 Exercises from Modern Assembly Language Programming with the ARM processor by Larry D. Pyeatt. I was doing the other problems but I'm stuck on these two specifically. I know how to convert base 10 to 2 and to 16 (hexa). However, I don't know how to convert hexadecimal to base 21. Other websites have given me the answer but I want to know the step-by-step process on the conversion to base 21. Please help me.

1.2 Perform the base conversions to fill in the blank spaces in the following table:

Base 10	Base 2	Base 16	Base 21
23	10111	17
19	010011	13
2747	101010111011	ABB
			2HE

1.8 Given the following binary string:01001001 01110011 01101110 00100111 01110100 00100000 01000001 01110011 01110011 01100101 01101101 01100010 01101100 01111001 00100000 01000110 01110101 01101110 00111111 00000000

(a) Convert it to a hexadecimal string.

(b) Convert the first four bytes to a string of base ten numbers.

(c) Convert the first (little-endian) halfword to base ten.

(d) Convert the first (big-endian) halfword to base ten.

(e) If this string of bytes were sent to an ASCII printer or terminal, what would be printed?