Here's how to calculate it:

* Convert grams to kilograms: 100 grams = 0.1 kilograms

* Use the acceleration due to gravity: The acceleration due to gravity on Earth is approximately 9.8 m/s².

* Apply Newton's Second Law: Force = mass x acceleration

* Calculate the force: Force = 0.1 kg x 9.8 m/s² = 0.98 Newtons

Therefore, the force pulling a 100 gram mass down is approximately 0.98 Newtons.