The HCF and LCM of two numbers are 145 and 2175 respectively. If the first number is 435, find the second number.

Answer

To find the second number given the HCF, LCM, and the first number, we can use the relationship:

\[ \text{HCF} \times \text{LCM} = \text{First Number} \times \text{Second Number} \]

### Step-by-Step Solution:

1. **Identify the given values:**
- HCF = 145
- LCM = 2175
- First Number = 435
- Second Number = ?

2. **Set up the equation using the relationship:**
\[ \text{HCF} \times \text{LCM} = \text{First Number} \times \text{Second Number} \]
Substituting the known values:
\[ 145 \times 2175 = 435 \times \text{Second Number} \]

3. **Calculate the left side of the equation:**
\[ 145 \times 2175 = 315375 \]

4. **Substitute this value back into the equation:**
\[ 315375 = 435 \times \text{Second Number} \]

5. **Solve for the Second Number:**
To find the Second Number, divide both sides by 435:
\[ \text{Second Number} = \frac{315375}{435} \]

6. **Perform the division:**
\[ \text{Second Number} = 725 \]

### Final Answer:
The second number is **725**.