1. Least Count of a Scale (Ruler): The least count of a scale (ruler) is the smallest measurement that can be read or observed accurately using the scale's markings. It depends on the precision and gradations of the scale.

Here's how you can check the least count of a scale:

a. Identify the smallest division on the scale: Examine the markings on the scale and identify the smallest division between two consecutive markings. This is the smallest measurement that the scale can represent.

b. Measure the smallest length: Take a precise measurement using the scale, ensuring that you align the object's edge with one of the scale's markings. Note down this measurement.

c. Calculate the least count: The least count of the scale is equal to the smallest measurement divided by the number of divisions.

For example, if the smallest division on the scale is 1 millimeter (mm) and you measured the smallest length to be 0.5 mm, the least count would be:

Least Count = 0.5 mm / 1 = 0.5 mm

2. Least Count of a Clock (Timepiece): The least count of a clock or timepiece is the smallest time interval that the clock can measure accurately. It depends on the precision of the clock's movement.

Here's how you can check the least count of a clock:

a. Start the clock: Set the clock to the exact time.

b. Observe the clock: Watch the second hand of the clock carefully and note the time when the second hand completes one full revolution (60 seconds).

c. Calculate the least count: The least count of the clock is equal to the time taken for one full revolution of the second hand (60 seconds) divided by the number of divisions on the clock's dial.

For example, if the clock's dial has 60 divisions for each minute (1 division per second), the least count would be:

Least Count = 60 seconds / 60 = 1 second

So, the least count of the clock is 1 second.

By following these steps, you can check and calculate the least count of a scale and a clock to understand their precision and accuracy in measuring length and time, respectively.