Multiples (Lowest Common Denominator = LCD)
What is the LOWEST common denominator (LCD) of:
2 and 5
10
Create equivalent fractions for:
1/2 and 1/3
1/2 X 3/3 = 3/6
1/3 X 2/2 = 2/6
1/3 + 1/5 = ?
8/15
Cindy finished 1/3 of her homework before dinner and she finished 1/6 of her homework after dinner. How much of her homework does she still have left to do?
1/3 + 1/6 = ?
2/6 + 1/6 = 3/6 (which is equivalent to 1/2)
Cindy still has 1/2 of her homework left to do.
Fred drank 1/4 quart of chocolate milk and George drank 2/3 quart of chocolate milk. How much did they drink together?
1/4 + 2/3 = ?
3/12 + 8/12 = 11/12
Together Fred and George drank 11/12 quarts of chocolate milk.
What is the LOWEST common denominator (LCD) of:
3 and 7
21
Create equivalent fractions for:
1/4 and 2/7
1/4 X 7/7 = 7/28
2/7 X 4/4 = 8/28
1/2 - 2/7
3/14
Thidwick brought 2/3 gallons of lemonade and 3/5 gallons of iced tea to a party. How many gallons of drinks did he bring to the party?
2/3 + 3/5 = ?
10/15 + 9/15 = 19/15 = 1 and 4/15
Thidwick brought 1 and 4/15 gallons of drinks to the party.
5/8 + 4/8 + 6/8 = 15/8 = 1 and 7/8
The principal will use 1 and 7/8 tanks of gas.
What is the LCD of:
4 and 6
12
Create equivalent fractions for:
2/5 and 3/4
2/5 X 4/4 = 8/20
3/4 X 5/5 = 15/20
2/3 + 2/7 = ?
20/21
Dr. Trout had 2/3 liter of medicine. He used 1/5 liter for a patient. How much medicine did he have left?
2/3 - 1/5 = ?
10/15 - 3/15 = 7/15
Dr. Trout had 7/15 liters of medicine left.
Rapunzel had 1 and 1/2 meters of hair on her head. She cut off 3/8 meters because it gave her a headache. How much hair did she have left?
1 and 1/2 - 3/8 = ?
3/2 - 3/8 = ?
12/8 - 3/8 = 9/8 = 1 and 1/8
Rapunzel had 1 and 1/8 meters of hair left.
What id the LCD of:
6 and 9
18
Create equivalent fractions for:
3/4 and 5/6
3/4 X 3/3 = 9/12
5/6 X 2/2 = 10/12
(half points for equivalent fractions with any other denominator, such as 24ths)
1 and 1/4 - 2/3 = ?
7/12
Farmer Brown had 1 and 1/8 kg of fertilizer. He used some in his garden and had 2/3 kg left. How much fertilizer did he use on his garden?
1 and 1/8 - 2/3 = ?
9/8 - 2/3 = ?
27/24 - 16/24 = 11/24
Farmer Brown used 11/24 kg of fertilizer in his garden.
Esmerelda baked a pumpkin pie. She ate 1/4 of it, her brother ate 1/3 of it and she gave the rest to her dog. How much of the pie did Esmerelda give to her dog?
1 whole pie - (1/4 + 1/3) = ?
1 whole pie - (3/12 + 4/12)
1 whole - 7/12 = ?
12/12 - 7/12 = 5/12
Esmerelda's dog ate 5/12 of the pumpkin pie!
What is the LCD of:
2 and 8
8
Create equivalent fractions for:
3/4 and 3/8
3/4 X 2/2 = 6/8
3/8 can remain 3/8 !!
(half points for correct equivalent fractions with any other denominator, such as 16ths, 24ths or 32nds)
1/4 + 3/4 + 2/5 = ?
(1/4 + 3/4 = 4/4 = 1 whole)
1 whole + 2/5 = 1 and 2/5
No equivalent fractions needed!
Susie used maple syrup to make candy and to make ice cream. She used 1 and 1/3 cups of maple syrup for the candy, which was 1/5 cups more than she used to make ice cream. How much maple syrup did Susie use to make ice cream?
The candy used more, so the ice cream used less!
1 and 1/3 - 1/5 = ?
4/3 - 1/5 = ?
20/15 - 3/15 = 17/15 = 1 and 2/15
Susie used 1 and 2/15 cups of maple syrup to make ice cream.
Noah picked 3/5 kg of blueberries. He picked 1/10 kg less than David. How many kg of blueberries did David pick?
Noah picked less, so David picked more!
3/5 + 1/10 = ?
6/10 + 1/10 = 7/10
David picked 7/10 kg of blueberries.