Michael has 225 milliliters of a liquid. To find out the number of grams of calcium in this liquid, Michael multiplies the volume by 0.015. When he writes the number representing the amount of calcium in the liquid, how many significant digits will the number have?

In mathematical operations with significant figures the answer must reflects the reliability of the least precise number. 225 has three significant figures, whereas 0.015 has two -leading zeroes are not significant figures, so our answer must have two significant figures to reflect the reliability of the number 0.015, which has two significant figures.

[tex]225*0.015=3.4[/tex]

We can conclude that  the number representing the amount of calcium in the liquid will have two significant figures.