A circuit joins gates: one gate's output becomes another's input. An expression describes the same thing in writing.

1. Q = (A AND B) OR NOT C
2. Work out the brackets first: A AND B.
3. Then NOT C.
4. Then OR the two results.

Without brackets, NOT is done first, then AND, then OR (just as × comes before + in maths). Questions usually add brackets to make the order clear.

For a three-input truth table, add a working column for each bracket. It saves mistakes.

Build a circuit for Q = (A AND B) OR NOT C. The target column shows what Q should be; the board tells you when every row matches.

Then try Q = (A OR B) AND NOT (A AND B). Its truth table is the same as one single gate: which one?

Start at the inputs and write what each gate does, working towards Q. Put each gate's result in brackets before it feeds the next gate.

From a truth table, look at the rows where Q = 1. If Q is 1 only when A = 1 and B = 0, then Q = A AND NOT B.