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Unknown (math) facts for kids

Kids Encyclopedia Facts

An unknown is a number or value that we don't know yet. We often need to find these unknown values when solving problems. They are very important in mathematics and science.

In algebra, which is a part of mathematics, unknowns are usually called variables. We use symbols like x, y, or z to represent them. Imagine you have a puzzle where you need to find a missing number; that missing number is an unknown.

In science, especially physics, letters from the Roman or Greek alphabet often stand for unknown values. For example, in the famous equation E=mc^2, the letter m is an unknown representing mass. The letter E is also an unknown, representing the amount of energy. If you know the values for all but one unknown in an equation, you can usually figure out the last one. This is called solving the equation.

Not all letters in science equations are unknowns. Some letters represent physical constants. These are values that are always the same and do not change. In the equation E=mc^2, c is a constant. It represents the speed of light, which is about 186,000 miles per second. Because c is a very large number, the formula E=mc^2 shows that even a tiny bit of mass can create a huge amount of energy in an atomic reaction.

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Unknown (math) Facts for Kids. Kiddle Encyclopedia.