Symbols & alphabet

• $\pm$Plus minusboth signs possible$x = 3 \pm 1$
• $\approx$Approximatelyrounded, not exact$\pi \approx 3{,}14$
• $\neq$Not equaldifferent$3 \neq 5$
• $\leq$Less or equalat most$x \leq 10$
• $\sqrt{\phantom{x}}$Square rootinverse of squaring$\sqrt{16} = 4$
• $\infty$Infinitywithout end, not a number$x \to \infty$
• $\Delta$Deltachange of a quantity$\Delta v = v_2 - v_1$
• $\sum$Summationadd everything up$\sum_{i=1}^{4} i = 10$
• $\in$Element ofbelongs to the set$3 \in \{1, 2, 3\}$
• $\subseteq$Subsetfully contained in$A \subseteq B$
• $\cup$Unioneverything from both sets$A \cup B$
• $\cap$Intersectiononly what is shared$A \cap B$
• $\emptyset$Empty setset with no elements$A \cap B = \emptyset$
• $\to$Tends toapproaches$\tfrac{1}{x} \to 0$
• $\land$Andboth must be true$A \land B$
• $\lor$Orat least one true$A \lor B$
• $\lnot$Notnegation$\lnot A$
• $|x|$Absolute valuedistance from zero$|{-5}| = 5$
• $n!$Factorialproduct 1 to n$4! = 24$
• $\int$Integralarea under the graph$\int_0^2 x\,dx = 2$

When the Latin alphabet runs out, maths and physics reach for the Greek one. These are the letters you will meet most often.