1. **Definition of Decimals:** Decimals are numbers expressed in the base-10 system using a decimal point to separate the whole number part from the fractional part. For example, $3.14$ means 3 whole units and 14 hundredths. 2. **Definition of Fractions:** Fractions represent parts of a whole and are written as $\frac{a}{b}$ where $a$ is the numerator (part) and $b$ is the denominator (whole). For example, $\frac{3}{4}$ means 3 parts out of 4 equal parts. 3. **Definition of Power Numbers (Exponents):** Power numbers or exponents express repeated multiplication of a base number. Written as $a^n$, it means multiply $a$ by itself $n$ times. For example, $2^3 = 2 \times 2 \times 2 = 8$. These concepts are fundamental in understanding numbers and their operations in mathematics.