Im having a hard time understanding how to write my sig fig and rounding to the 10th on my lab. I need some guidance on how to write it.

Im having a hard time understanding how to write my sig fig and rounding to the 10th on my lab. I need some guidance on how to write it.

ALUMINUM METAL

Pre-weighed aluminum metal 

sample mass (mmetal)

 19.99g

Temperature of boiling water and metal sample in the pot (Ti(metal))

 91