feat: add answers to Q16-Q20 powers of two and multi-byte interpretation

Author: Konvaly

number-systems/Part-2.md

@@ -7,16 +7,22 @@ The goal of these exercises is for you to gain an intuition for binary numbers.
 The answers to these questions will require a bit of explanation, not just a simple answer.
 
 Q16: How can you test if a binary number is a power of two (e.g. 1, 2, 4, 8, 16, ...)?
-Answer:
+Answer: A power of two in binary has only one 1 bit, followed by zero or more 0 bits: 2² = 4 = 100₂, 2⁴ = 16 = 10000₂
 
 Q17: If reading the byte 0x21 as an ASCII character, what character would it mean?
-Answer:
+Answer: (2 × 16) + (1 × 1) = 32 + 1 = 33₁₀ ASCII value 33 = character '!'
 
 Q18: If reading the byte 0x21 as a greyscale colour, as described in "Approaches for Representing Colors and Images", what colour would it mean?
-Answer:
+Answer: 0x21 = 33₁₀ If we consider greyscale range: 0 (black) to 255 (white), 33 is very close to 0, so it's a very dark grey
 
 Q19: If reading the bytes 0xAA00FF as a sequence of three one-byte decimal numbers, what decimal numbers would they be?
-Answer:
+Answer: 0xAA = (10 × 16) + (10 × 1) = 160 + 10 = 170₁₀
+0x00 = (0 × 16) + (0 × 1) = 0₁₀
+0xFF = (15 × 16) + (15 × 1) = 240 + 15 = 255₁₀
 
 Q20: If reading the bytes 0xAA00FF as an RGB colour, as described in "Approaches for Representing Colors and Images", what colour would it mean?
-Answer:
+Answer: Red = 170₁₀ (high, but not maximum)
+Green = 0₁₀ (none)
+Blue = 255₁₀ (maximum)
+Red + Blue = violet/purple
+Since Blue is max and Red is substantial, it leans toward Blue-Violet