Estimating Sums and Differences
Estimate the sum of 8/10 and 1/9. Write an equation.
1 + 0 = 1
1/12 + 3/8 =
11/24
2 5/6 + 1 5/6 =
4 2/3
5 5/8 - 3 1/4 =
2 3/8
Martina says that (3 ⅓ + 2 1/9) - 2 ⅓
is equal to a whole number. Do you agree? Explain.
No. The answer is 3 1/9. I added the numbers in parentheses and got 5 4/9. I then subtracted 2 1/3 from that and got 3 1/9. So the answer is not a whole number.
What is the estimated sum of 1/5 + 1/3?
0 + 1/2 = 1/2
7/8 - 2/3 =
5/24
2 1/4 + 5 11/12 =
8 1/6
12 - 3 ⅘
8 1/5
Harold has two pieces of wood. One is ⅜ foot long, and the other is ¼ foot long. Write ⅜ and ¼ using a common denominator. Then give the total length of both pieces.
3/8 and 2/8
The total length of both pieces is 5/8 foot.
What is the estimated difference of 3 11/24 - 1 1/9?
3 1/2 - 1 = 2 1/2
2/5 + 3/10 =
7/10
6 2/3 + 5 5/6 =
12 1/2
9 7/10 - 3 4/5 =
5 9/10
Sophia has ⅓ cup of flour for a recipe. She needs to use ¾ more. How much flour does Sophia need for this recipe?
1 1/12 cup
1/3 + 3/4 = 1 1/2
What is the estimated difference of 6 3/5 - 2 8/14 =
6 1/2 - 2 1/2 = 4
1/9 + 5/6 =
17/18
8 4/10 + 2 3/5 =
11
9 - 3 3/8 =
5 5/8
For a bicycle ride, Kerry rode 9/10 mile and Aidan rode ⅗ mile.
Estimate how much longer Kerry rode than Aidan.
1 - 1/2 = 1/2
About 1/2 mile longer
Estimate the sum of 12 2/3 + 8 11/23
12 1/2 + 8 1/2 = 21
3/4 - 5/12 =
1/3
3 1/3 + 9 11/12 =
13 1/4
12 3/4 - 7 1/2 =
5 1/4
Desmond made a square tile with all 4 sides measuring 6 ⅔ centimeters. What is the perimeter of this square tile?
26 2/3 cm