Rounding
Round 628 to the nearest ten
630
What is the answer to an addition problem called?
sum
What is the answer to a subtraction problem called?
difference
Find the sum
545+139=_____
684
What property says that when you add zero to a number, the sum is that number.
ex) 9+0=9
Identity (zero) Property
Round 704 to the nearest hundred
700
Estimate. Then find the sum
356+442=____
Estimate: 800
Sum: 798
Use rounding to estimate the differences. Show works
445-112=
400-100=300
Find the difference
437-184=_______
253
What property says you can change the order of the addends and still get the same sum?
ex) 3+8= 11 8+3=11
Commutative (order) Property
DOUBLE JEOPARDY
Select the numbers that round to 200 when rounded to the nearest hundred.
A. 178
B. 242
C. 267
A. 178
B. 242
Estimate. Then find the sum
164+235=____
Estimated Sum: 400
Sum: 399
Use rounding to estimate differences.
394 - 147=
240
Find the sum.
39+243=
282
Even or Odd?
7 + 2 =
odd
Tim and Owen are playing a game. Tim scored 486 points and Owen scored 654. Tim estimates he needs about 200 points more to reach Owen's score. Did he estimate to the nearest ten or nearest hundred?
Nearest hundred
Jay collected 139 cans for recycling on Monday, and 94 on Tuesday. About how many cans did he collect altogether?
about 230
**DOUBLE JEOPARDY**
The 3rd grade classes decided to have a reading contest and the result is as follows.
Mrs. Vay's class - 273 books
Mrs. Hong's class - 402 books
Mrs. Ward's class - 247 books
- About how many fewer books did Mrs. Vay's class read than Mrs. Hong's?
About 130 books
Cathy was making paper flowers for friends. In January, she gave away 246 paper flowers to her family. In February, she gave away 418 paper flowers to her friends. In March, she gave away 349 paper flowers to her neighbors. How many more flowers did she give away in January than March?
103 paper flowers
Even or Odd?
4 + 2 =
even
James sold 237 cups of lemonade at his lemonade stand. What is 237 rounded to the nearest ten? Include the label.
240 cups
There are 294 boys and 332 girls in the Emerson school. About how many students are in the school?
about 620 students
Lea sold 336 muffins at the bake sale. Noah sold 287 muffins. Noah estimates that he sold 50 fewer muffins than Lea. How did he estimate? Explain.
Noah rounded to the nearest ten.
He rounded 336 to 340 and 287 to 290.
Then he subtracted 340-290= 50
Mike drove 159 miles on Saturday. On Sunday he drove 224 miles. How many miles did he drive on Saturday and Sunday?
383
What property states that you can group addends in different ways and still get the same sum.?
(2+3) + 4 = 2 + (3+4)
Associative (grouping) Property