Estimate and Find Common Denominators
Choose all the numbers that could be common denominators for 2/3 and 7/9.
6, 9, 18, 27, 30
9, 18, and 27
Find the sum of 1/9 + 5/6 = ?
What is the least common multiple (LCM) that is the same?
LCM = 18
2/18 + 15/18 = 17/18
Find the difference:
3/4 - 2/5 = ?
15/20 - 8/20 = 7/20
Find the sum:
5 2/5 + 4 1/2 = ?
5 4/10 + 4 5/10 = ?
9 9/10
Find the difference:
5 6/7 - 1 1/2 = ?
5 12/14 - 1 7/14 = ?
4 5/14
Find the sum or difference:
1/2 - (1/8 + 1/8) = ?
1/2 - (2/8) = ?
4/8 - 2/8 = 2/8 = 1/4
Choose all the numbers that could be common denominators for 1/9 and 1/2.
11, 16, 18, 36, 45
18 and 36
Find the sum:
1/12 + 7/9 = ?
3/36 + 28/36 = 31/36
Find the difference:
17/18 - 2/3 = ?
17/18 - 12/18 = 5/18
Find the sum:
3 7/8 + 5 2/3 = ?
3 21/24 + 5 16/24 = ?
8 37/24 = 9 13/24
Find the difference:
8 1/4 - 7/8 = ?
8 2/8 - 7/8 = ?
7 10/8 - 7/8 = ?
7 3/8
Find the sum or difference:
(3/4 + 2/3) - 5/8 = ?
(9/12 + 8/12) - 5/8 = ?
17/12 - 5/8 = 34/24 - 15/24 = 19/24
Find a common denominator for 6/7 and 1/5.
Then write equivalent fractions with the common denominator.
35
6/7 = 30/35
1/5 = 7/35
Find the sum: 4/18 + 2/9 = ?
4/18 + 4/18 = 8/18 = 4/9
Find the difference:
3/5 - 1/3 = ?
9/15 - 5/15 = 4/15
Find the sum:
15 1/3 + 1 5/12 = ?
15 4/12 + 1 5/12 = ?
16 9/12 = 16 3/4
Find the difference:
9 1/2 - 6 9/10 = ?
9 5/10 - 6 9/10 = ?
8 15/10 - 6 9/10 = ?
2 6/10 = 2 3/5
Find the sum or difference:
(5 1/2 + 2 3/4) - 3 1/2 = ?
(5 2/4 + 2 3/4) - 3 1/2 = ?
8 1/4 - 3 1/2 = ?
8 1/4 - 3 2/4 = 7 5/4 - 3 2/4 = ?
4 3/4
Estimate by replacing each fraction with 0, 1/2, or 1.
4/18 + 3/7 = ?
4/18 is closest to 0
3/7 is closest to 1/2
0 + 1/2 = about 1/2
What fraction is missing from this equation?
5/6 - ? = 3/12
7/12
Find the difference:
8/8 - 4/9 = ?
72/72 - 32/72 = 40/72 = 5/9
Ken used 1 3/8 cups of walnuts and 1 3/4 cups of raisins to make trail mix. How many total cups of trail mix did he make?
1 3/8 + 1 3/4 = ?
1 3/8 + 1 6/8 = ?
2 9/8 = 3 1/8
In the problem 7 − 3 5/12, how do you rename the 7?
What is the difference?
Since 12/12 = 1, I can rename the 7 as 6 12/12.
6 12/12 - 3 5/12 = 3 7/12
Find the sum or difference:
10 5/16 - (5 1/4 + 2 9/16) = ?
10 5/16 - (5 4/16 + 2 9/16) = ?
10 5/16 - 7 13/16 = ?
10 5/16 - 7 13/16 = 9 21/16 - 7 13/16 = ?
2 8/16 = 2 1/2
Julia has to mow two yards. She will need 13/16
gallon of gas to mow the first yard and 2/5
gallon to mow the second yard. She has 1 1/2
gallons of gas in her can. Does she have enough to mow both yards? Explain.
Yes. The first yard takes less than 1 gallon. The second takes less than 1/2 gallon. So the two yards will take less than 1 1/2 gallons altogether.
Mary has three lengths of cable, 3/6 yard long, 1/4 yard long, and 1/3 yard long. Which two pieces together make a length of 20/24 yard?
3/6 and 1/3
Paul’s dad made a turkey pot pie for dinner on Wednesday. The family ate 4/8 of the pie. On Thursday after school, Paul ate 2/16 of the pie for a snack. What fraction of the pie remained?
3/8 of the pie
Trish drove 18 1/8 miles yesterday. She drove 13 2/3 miles today. Write an addition sentence to show how many miles Trish drove in all and solve.
18 1/8 + 12 2/3 = ?
18 3/24 + 12 16/24 = ?
31 19/24 miles in all
Micah’s rain gauge showed that 9 1/2 centimeters of rain fell last month. This month, the rain gauge measured 10 3/10 centimeters. How many more centimeters of rain fell this month?
10 3/10 - 9 1/2 = ?
10 3/10 - 9 5/10 = ?
9 13/10 - 9 5/10 = ?
8/10 = 4/5 cm more rain
Suzy spent 6 7/8 days working on her English paper, 3 1/6 days doing her science project, and 1 1/2 days studying for her math test. How many more days did Suzy spend on her English paper and math test combined than on her science project?
(6 7/8 + 1 1/2) - 3 1/6 = ?
(6 7/8 + 1 4/8) - 3 1/6 =?
8 3/8 - 3 1/6 = ?
8 9/24 - 3 4/24 = ?
5 5/24 more days