What an Exponent Does
An exponent is repeated multiplication: 2⁵ is 2 × 2 × 2 × 2 × 2 = 32. That definition covers positive whole numbers, and everything else — zero, negatives, fractions — follows from making the rules stay consistent.
Exponent Rules Chart
| Rule | Form | Example |
|---|---|---|
| Product | xa × xb = xa+b | 2³ × 2² = 2⁵ = 32 |
| Quotient | xa / xb = xa−b | 2⁵ / 2² = 2³ = 8 |
| Power of a power | (xa)b = xab | (2³)² = 2⁶ = 64 |
| Power of a product | (xy)a = xaya | (2×3)² = 4×9 = 36 |
| Zero exponent | x0 = 1 | Any non-zero base |
| Negative exponent | x−a = 1 / xa | 2−3 = 1/8 = 0.125 |
| Fractional exponent | xa/b = b√(xa) | 82/3 = 4 |
Why x0 = 1
Follow the quotient rule: xa / xa = xa−a = x0. Any number divided by itself is 1, so x0 must be 1. The same logic gives negative exponents: x2 / x5 = x−3, and computing the division directly gives 1/x³.
00 is the one genuinely contested case. It is defined as 1 in combinatorics and most programming languages, and left undefined in analysis, because the limit depends on how you approach it.
Powers Chart
| n | 2n | 3n | 5n | 10n |
|---|---|---|---|---|
| 1 | 2 | 3 | 5 | 10 |
| 2 | 4 | 9 | 25 | 100 |
| 3 | 8 | 27 | 125 | 1,000 |
| 4 | 16 | 81 | 625 | 10,000 |
| 5 | 32 | 243 | 3,125 | 100,000 |
| 8 | 256 | 6,561 | 390,625 | 100,000,000 |
| 10 | 1,024 | 59,049 | 9,765,625 | 10,000,000,000 |
Where Exponents Appear
Compound interest, population growth, radioactive decay, sound intensity, earthquake magnitude, computer memory sizes and algorithmic complexity all rest on exponents. The reason is that exponential growth describes anything whose rate of change is proportional to its current size — which covers a remarkable share of natural and financial processes.
Frequently Asked Questions
What does a negative exponent mean?
Reciprocal, not negative result. 2−3 is 1/8, a positive number. Only a negative base can make the result negative.
How do I calculate a fractional exponent?
The denominator is the root and the numerator is the power: 82/3 means the cube root of 8, squared — 2² = 4.
Is 2³ the same as 3²?
No. 2³ = 8 and 3² = 9. Exponentiation is not commutative, unlike multiplication.