Multiplying Fractions and Mixed Numbers
Its back! Yayyyy!!!
So…I am currently teaching multiplying fractions and mixed numbers to my upper level sixth graders. We teach how to multiply fractions with a Hershey chocolate bar, and we teach how to multiply mixed numbers with a cookie recipe that we enlarge 2 1/2 times. They actually bring the ingredients and we mix it up and I bring them cookies the next day. (I do not deserve credit for thinking of this, the teachers at my school did this before I got there.) So here are some problems for you…
1. 3/4 x 5/6 =
Get the answer and also tell me if you remembered anything special you could do to make it easier.
2. 5 1/3 x 7 1/2 =
Get the answer and tell me how you did it.
November 20th, 2009 at 1:18 pm
Ok, so you multiple the tops across and the bottoms across so – 15/24 simplified = 5/8
And the other one, you get them both in fraction form and do the same thing – 240/6 simplified =40!
Do I win?
November 21st, 2009 at 12:46 am
5/8: numerator of first and denominator of second could be reduced (both divided by 3), so 3/4 x 5/6 became 1/4 x 5/2. Then multiply across (1×5 and 4×2) and you get 5/8. Do it the long way and get 15/24, then reduce down (divide by common number of 3) and get 5/8.
40: 5 1/3 equals 16/3. 7 1/2 equals 15/2. 16/3 x 15/2. Use the same process as the first to reduce down: 8/1 x 5/1…or 8 x 5. Equals 40.
Took me a minute to remember what to do, and I’m sure I don’t have the terminology right! Yay for the return of AYSTASG!
November 23rd, 2009 at 8:12 am
i would like to be smarter than a sixth grader.
November 23rd, 2009 at 1:06 pm
1) 3/4 x 5/6 = 3×5 / 4×6 = 15/24 = 5/8
2) 5 1/3 x 7 1/2 = 16/3 x 15/2 = 240/6 = 40
November 30th, 2009 at 12:16 am
Great answers!