Estimating Sums
67 + 12.5
70 + 13 = 83
10 - 6.9
10 - 7 = 3
5.1 + 2.2
7.3
1.50 - 1.05
0.45
What is the most important thing to remember when adding or subtracting decimals?
LINE UP THE DECIMALS
579 + 2.3
580 + 2 = 582
12.2 - 3.3
12 - 3 = 9
10 + 3.28
13.28
2.63 - 1.22
1. 41
If you line up the decimals, and you have place values without a number, what number do you add?
0
111 + 67.67
110 + 68 = 178
38 - 9.9
40 - 10 = 30
9.12 + 10.01
19.13
55.55 - 22.22
33.33
BONUS: Which number is the whole number?
3.455
3
What does it mean to estimate?
To estimate means to round both numbers to the closest place value (tens, hundreds, thousands).
What is a difference? What is a sum?
A difference is the total when you subtract. A sum is the total when you add.
300 + 123.45
423.45
Veronika starts with $10.00 and spends $5.80. How much does she have left?
$4.20
What was one of the snacks on the price list of our Fall Festival Card activity on Thursday/Friday?
Hamburger
Hot Dog
Slice of Pizza
BBQ Sandwich
Deep Fried Pickle
Deep Fried Cookie
Pumpkin Pie
Soda
Hot Chocolate
Which estimate is closer to the actual answer?
Problem: 209 + 55.5
A) 210 + 16
B) 200 + 50
A) 210 + 16
Which estimate is closer to the actual answer?
Problem: 345 - 23.0
A) 350 - 23
B) 350 - 20
B) 350 - 20
67.8 + 12.2
80.00
Ms. Baio is given $20.00 to buy materials for the school costume party. She buys streamers that cost $5.00, plates that cost $2.50, cups that cost $2.00, candy for .50, and a costume that costs $12.50.
Does she have enough money for all of these items? Explain.
No, the items cost $22.50 and Ms. Baio only has $20.00.
Multiply:
56 X 100
5600