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DEMO: Boolean logic

Worked examples

• TRUE AND TRUE = TRUE, because both inputs are true.
• FALSE OR FALSE = FALSE, because neither input is true.
• NOT (TRUE OR FALSE) = NOT TRUE = FALSE.
• Let $A = 0$, $B = 1$: A OR (NOT B) = $0$ OR $0$ = $0$.
• OR with inputs $1, 0$ gives $1$; AND with inputs $1, 0$ gives $0$.
• Let $A = 0$, $B = 1$, $C = 1$: (A AND B) OR C = $0$ OR $1$ = $1$.

Key points

• AND is true only when both inputs are true.
• One input here is false.
• OR is true when at least one input is true.
• One input here is true.
• Work out the brackets first.
• TRUE AND FALSE = FALSE, then NOT flips it.
• Work out NOT B first.
• NOT $0$ = $1$, so the expression is $1$ AND $1$.
• Check the inputs $1, 0$: the output must be $0$.
• OR gives $1$ for $1, 0$; NOR gives $0$ for it but $1$ for $0, 0$.
• Work out the brackets first: $1$ OR $0$.
• Then $1$ AND $C$, where $C = 0$.

Teacher video

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