Replace `'square'` in each of the following by the correct number :
`7/18=42/square`

Answer

To solve the equation \( \frac{7}{18} = \frac{42}{\text{square}} \), we need to find the value of 'square' that makes the equation true.

### Step-by-Step Solution:

1. **Set up the equation**: We start with the equation \( \frac{7}{18} = \frac{42}{\text{square}} \).

2. **Cross-multiply**: To eliminate the fractions, we can cross-multiply. This means we multiply the numerator of the first fraction by the denominator of the second fraction and vice versa. So, we have:
\[ 7 \times \text{square} = 18 \times 42 \]

3. **Calculate the right side**: Now, we calculate \( 18 \times 42 \):
\[ 18 \times 42 = 756 \]

4. **Set up the equation**: Now we have:
\[ 7 \times \text{square} = 756 \]

5. **Solve for 'square'**: To find 'square', we divide both sides of the equation by 7:
\[ \text{square} = \frac{756}{7} \]

6. **Calculate the division**: Now, we perform the division:
\[ \frac{756}{7} = 108 \]

7. **Final answer**: Therefore, the value of 'square' is:
\[ \text{square} = 108 \]

### Final Answer:
The correct number to replace 'square' is **108**.