Answer:
0.09
Explanation:
First off, we can write 0.9 as a fraction. Reading this, we would say "nine tenths"; this means the number in fraction form is 9/10.
The word "of" in mathematics means we multiply. Thus when we take 1/10 "of" 9/10, we multiply the two:
1/10(9/10)
To multiply fractions, multiply the numerators and multiply the denominators:
1/10(9/10) = (1*9)/(10*10) = 9/100
Converting this back to a decimal, we read 9/100 as "nine one-hundredths"; this means decimal form is 0.09.