Question

Which number is not rational
0.625
0.5
square root of 5
3

Answer 1

A rational number is defined as a number that can be expressed as the quotient of two integers (where the denominator is not zero).

- **0.625** can be expressed as \( \frac{625}{1000} \), which is rational.
- **0.5** can be expressed as \( \frac{1}{2} \), which is rational.
- **3** can be expressed as \( \frac{3}{1} \), which is rational.
- **The square root of 5** (approximately 2.236) cannot be expressed as a fraction of two integers; hence, it is an irrational number.

So, the number that is not rational is **the square root of 5**.