Find: The common logarithm of 21 (Log 21)

- Cursor to 21 on D
- Mantissa = .322 at cursor on L
- Logarithm is 1.322 (Characteristic is 1, because 21 is between 10 (whose characteristic = 1) and 100 (whose characteristic = 2).
- Or we can say 10 to the 1.322 power = 21.

Find: Log 2100

- Mantissa is still .322
- Characteristic is 3, because 2100 is between 1,000 (Characteristic = 3) and 10,000 (Characteristic = 4).
- Logarithm is 3.322
- 10 to the 3.322 power is 2100.

Find: Log 2.1

- Mantissa is still .322
- Characteristic is now 0
- Logarithm is 0.322