# Delta facts for kids

Kids Encyclopedia Facts
 Greek alphabet Other letters Αα Alpha Νν Nu Ββ Beta Ξξ Xi Γγ Gamma Οο Omicron Δδ Delta Ππ Pi Εε Epsilon Ρρ Rho Ζζ Zeta Σσς Sigma Ηη Eta Ττ Tau Θθ Theta Υυ Upsilon Ιι Iota Φφ Phi Κκ Kappa Χχ Chi Λλ Lambda Ψψ Psi Μμ Mu Ωω Omega Ϝϝ Digamma Ⱶⱶ Heta Ϻϻ San Ϙϙ Koppa Ϡϡ Sampi Ϛϛ Stigma Ϸϸ Sho

Delta (uppercase/lowercase Δ δ), is a letter of the Greek alphabet, used to represent the "d" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 4. Letters that came from it include the Roman D and Cyrillic Д.

In mathematics, the upper-case letter Δ can be used as symbol to represent "change" in a variable (e.g., $\Delta x$). It can also be used to represent discriminant—a key algebraic expression used to determine the number of roots a polynomial has. The lower-case letter $\delta$, on the other hand, is often used to denote small quantities in proofs involving limit, a key concept on calculus is based on.

In molecular chemistry, the lower case Greek letter δ is used to represent a partial charge. This is always less than the unit charge associated with an ion, but has no real fixed value.

A river delta is so named because its shape approximates the upper-case letter delta.

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Delta Facts for Kids. Kiddle Encyclopedia.