how do you estimate the product or quotient for mixed fractions?
Read this first:
http://jamit.com.au/htmlFolder/FRAC1003.html#ImproperFrac
Convert the mixed numbers you are multiplying or dividing to "improper" fractions. When multiplying, multiply the numerators and denominators separately. You may want to convert the answer fraction back to a mixed number. When dividing, flip the divisor fraction upside down and then multiply.
Example: 1 1/2 x 2 1/2 = 3/2 x 5/2
= 15/4 = 3 3/4
1 1/2 divided by 2 1/2 = (3/2)/(5/2)
(3/2)x(2/5) = 6/10 = 3/5