The least number, that must be added to 1720 so as to obtain a perfect cube, is

Options

A. 7
B. 8
C. 11
D. 13

Answer

To find the least number that must be added to 1720 to obtain a perfect cube, we can follow these steps:

1. **Identify the nearest perfect cubes**:
The perfect cubes around 1720 are \( 11^3 = 1331 \) and \( 12^3 = 1728 \).

2. **Determine the perfect cube greater than 1720**:
Since 1720 is greater than 1331 but less than 1728, we will consider \( 12^3 = 1728 \) as the next perfect cube.

3. **Calculate the difference**:
We need to find the difference between 1728 and 1720 to determine how much we need to add:
\[ 1728 - 1720 = 8 \]

4. **Conclusion**:
The least number that must be added to 1720 to obtain a perfect cube is **8**.