Common Denominators
Rewrite the fractions 2/3 and 7/8 with a common denominator.
2/3 becomes 16/24
7/8 becomes 21/24
1/3 + 1/6 = ?
3/6 or 1/2
1 5/6 - 2/3 = ?
2/3 becomes 4/6
1 5/6 - 4/6 = 1 1/6
You new name is what you ate for dinner last night. What's your new name?
Now I'm hungry.
23 1/4 - 13 2/3 = ?
23 1/4 = 23 3/12, 13 2/3 = 13 8/12
23 3/12 becomes 22 15/12
22 15/12 - 13 8/12 = 9 7/12
Marnie wants to add the fractions 5/6 and 4/9. How can she do this?
Give them a common denominator of 18.
5/6 becomes 15/18
4/9 becomes 8/18
What object would you put on Mars to confuse scientists?
Look out, NASA!
The Sanchez family takes a 5-gallon jug of water on a camping trip. When they return from the trip, the jug has 1 1/8 gallons left. How much water did they use from the jug on their trip?
5 - 1 1/8
5 becomes 4 8/8
4 8/8 - 1 1/8 = 3 7/8
They used 3 7/8 gallons of water.
Mr. Guinea Pig has 1/4 lb. of hay in his cage. His owner brings him 2/3 lb. of hay. How much hay does Mr. Guinea Pig have now?
1/4 = 3/12, 2/3 = 8/12
3/12 + 8/12 = 11/12
Ms. Puche is taking inventory of her shoe collection. Half of her collection is colorful flats, 1/8 of her collection is sparkly shoes, and 1/3 of her collection is shoes with funky designs. What fraction of her collection remains for plain, boring shoes?
1/2 = 12/24, 1/8 = 3/24, 1/3 = 8/24
12/24 + 3/24 + 8/24 = 23/24
1/24 of her collection is plain, boring shoes.
How many licks does it take to get to the Tootsie Roll center of a Tootsie Pop?
Let's ask Mr. Owl!
Raj loves Jelly Belly jelly beans! He has 2/3 cup of watermelon jelly beans, 1/4 cup of kiwi jelly beans, and 1 1/2 cups of Dr. Pepper jelly beans. How many cups of jelly beans does he have all together?
2/3 = 8/12, 1/4 = 3/12, 1 1/2 = 1 6/12
8/12 + 3/12 + 1 6/12 = 1 17/12 = 2 5/12
He has 2 5/12 cups of jelly beans.
Anya has 2 1/3 cups of sugar. She needs 3/4 cups to make a batch of cookies. How much sugar will she have left?
2 1/3 = 2 4/12, 3/4 = 9/12
Change 2 4/14 to 1 16/12
1 16/12 - 9/12 = 1 7/12
She will have 1 7/12 cups of sugar left over.
Jennifer and Boris are comparing lengths of yarn for a knitting project. Jennifer has 5 3/7 inches of blue yarn and 3 1/9 inches of green yarn. Boris has 6 1/8 inches of green yarn and 5 6/14 inches of blue yarn. Who has more blue yarn?
Neither! 5 3/7 = 5 6/14
No addition of subtraction needed. You just compare, and everything else is unnecessary information!
Rewrite the fractions 1/3, 3/4, 5/9, and 7/12 with a common denominator
1/3 = 12/36
3/4 = 27/36
5/9 = 20/36
7/12 = 21/36
Rewrite the fractions 1/2, 3/4, 5/6, 7/8, and 11/12 with a common denominator.
The common denominator is 24!
1/2 becomes 12/24
3/4 becomes 18/24
5/6 becomes 20/24
7/8 becomes 21/24
11/12 becomes 22/24
Tanya has scraps of ribbon left over from an art project. She has 3/7 ft. of teal ribbon, 3/4 ft. of rainbow ribbon, and 1 1/2 ft. of sparkly ribbon. How much ribbon does she have left in all?
3/7 = 12/28, 3/4 = 21/28, and 1 1/2 = 1 14/28
12/28 + 21/28 + 1 14/28 = 1 47/28 = 2 19/28 ft.
She has 2 19/28 ft. of (gorgeous!) ribbon left.
You get to choose an animal to be your personal assistant. What do you choose?
I think I'd like a unicorn!
Bob, Dora, and Peppa are combining their fruits for a fruit salad. Bob has 3 1/3 cups of cherries, Dora has 2 1/5 cups of mangoes, and Peppa has 3 3/10 cups of peaches. How much fruit do they have for their fruit salad?
3 1/3 = 3 10/30, 2 1/5 = 2 6/30, 3 3/10 = 3 9/30
3 10/30 + 2 6/30 + 3 9/30 = 8 25/30 = 8 5/6
They have 8 5/6 cups of fruit.
(As long as Swiper doesn't swipe anything!)
Jeff and Joe are racing robots for a competition. Jeff's robot travels 9 1/3 feet, and Joe's robot travels 7 3/8 feet.
How far did their robots travel together?
How much farther did Jeff's robot travel than Joe's?
If they want their robots to travel a combined distance of 20 feet, how much farther do they need to travel?
9 1/3 = 9 8/24, 7 3/8 = 7 9/24
9 8/24 + 7 9/24 = 16 17/24 feet traveled together.
9 8/24 - 7 9/24 = 1 23/24 feet difference between Jeff's and Joe's robots.
20 - 16 17/24 = 3 7/24 feet more to reach their goal.
Rewrite the fractions 1/2, 2/3, and 6/11 with a common denominator.
The common denominator is 66.
1/2 becomes 33/66
2/3 becomes 44/66
6/11 becomes 36/66
2/3 + 7/12 + 13/15 = ?
2/3 = 40/60, 7/12 = 35/60, 13/15 = 52/60
40/60 + 35/60 + 52/60 = 127/60 = 2 7/60
Benson has a 12-pound bag of marbles. He gives 3 1/3 lbs. to his brother and 4 1/5 lbs. to his best friend. How many pounds of marbles does he have left?
3 1/3 = 3 5/15, 4 1/5 = 4 3/15
3 5/15 + 4 3/15 = 7 8/15
12 - 7 8/15
11 15/15 - 7 8/15 = 4 7/15 pounds of marbles left.
Reginald is recording a new 10-minute video for his followers. He records 3 1/5 minutes on Monday and 2 1/2 minutes on Tuesday. How much of his video does he have left to record?
3 1/5 = 3 2/10, 2 1/2 = 2 5/10
3 2/10 + 2 5/10 = 5 7/10 minutes recorded
10 - 5 7/10 = 4 3/10
He has 4 3/10 minutes left to record.
You just got sent to the principal's office! What did you do?
Personally, I think I asked too many questions.