Sign up for our US Editor's Picks newsletter to get all the biggest exclusive storiesA seemingly easy math puzzle making the ...

Incorrect Chemical Formulas: Sometimes an equation is unbalanced because the chemical formulas of the reactants or products are incorrect. For example, writing H2O2 (hydrogen peroxide) instead of H2O ...

It looks simple at first, but this math problem has the internet stumped. Don't be fooled - it demands more brainpower than ...

Before diving into the mixed practice itself, let's solidify the fundamentals. A variable is a symbol, usually a letter, that represents an unknown value. An expression is a combination of variables, ...