1. Let's start with **Consumer Arithmetic**: It involves calculations related to buying and selling, discounts, and taxes. 2. **Profit and Loss**: The formula for profit is $\text{Profit} = \text{Selling Price} - \text{Cost Price}$ and for loss is $\text{Loss} = \text{Cost Price} - \text{Selling Price}$. Profit or loss percentage is calculated as $\frac{\text{Profit or Loss}}{\text{Cost Price}} \times 100$. 3. **Wages and Salaries**: Wages are often calculated based on hours worked or output, while salaries are fixed amounts paid periodically. 4. **Overtime**: Overtime pay is usually calculated as $\text{Overtime Hours} \times \text{Overtime Rate}$. The overtime rate is often 1.5 or 2 times the normal hourly rate. 5. **Total Surface Area of Cuboid and Cube**: - For a cuboid with length $l$, width $w$, and height $h$, total surface area is $2(lw + lh + wh)$. - For a cube with side $a$, total surface area is $6a^2$. 6. **Standard Form**: Writing numbers as $a \times 10^n$ where $1 \leq a < 10$ and $n$ is an integer. 7. **Solving Equations and Simplifying Expressions**: Use algebraic rules like combining like terms, applying distributive property, and isolating variables. 8. **Adding Fractions**: Find a common denominator, convert fractions, then add numerators: $\frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}$. Each topic involves specific formulas and rules that help solve related problems efficiently.