Knowledge MountainA PLACE FOR EVERY CURIOUS MINDORIGINAL STARTER TRAIL / Computing foundations
Flip a bit. Watch an idea click.
FIELD NOTE / Computer Science
In unsigned binary, each position is a power of 2. From right to left, eight bits have weights 1, 2, 4, 8, 16, 32, 64, 128. Add the weights of positions holding 1. Thus 00001101₂ = 8 + 4 + 1 = 13₁₀. Eight unsigned bits represent 0 through 255.
A way to rememberOnly the lit switches pay into the total.
32 + 8 + 2 = 42.
FIELD NOTE / Computer Science
One hexadecimal digit represents four bits, because 2⁴ = 16. The digits are 0–9 followed by A–F for 10–15. Group binary from the right in fours: 0010 1111₂ becomes 2F₁₆, which is 2 × 16 + 15 = 47₁₀.
A way to rememberFour bits fit one hex seat.
A5₁₆: 1010 is 10 (A), and 0101 is 5.
FIELD NOTE / Computer Science
An algorithm is a sequence of unambiguous steps for a task. For a nonempty, odd-length list using one-based positions, the middle position is (n + 1) / 2. An even-length list has two central positions, so you must specify a policy: show both, pick the earlier one, or pick the later one. An empty list has no middle.
A way to rememberGood steps include the awkward cases.
Position 3: (5 + 1) / 2 = 3. For four names, positions 2 and 3 are the two central positions.
THE EIGHT-BIT PLAYGROUND
Each switch contributes its place value when it is on. Try representing 13, 42, and 255.
Unsigned eight-bit values only. The two hex digits are the two four-bit groups.
A practice check, not an exam. Pick an answer for each question, then read the reasoning.
Lesson completion is self-reported. Checkpoint scores reflect these practice questions, not a qualification or certified mastery.