What is another word for addition that we learned this chapter?
Sum
100
256 + 3 =
259
100
56 - 5 =
51
100
What is 159 rounded to the nearest ten?
160
100
Find the sum.
Then round each number to the nearest ten and check the answer is reasonable.
74 + 96 =
74 + 96 = 170
74 is about 70
96 is about 100
70 + 100 = 170
200
What is another word for subtraction that we learned this chapter?
Difference
200
875 + 6 =
881
200
131 - 8 =
123
200
What is 32 rounded to the nearest ten?
30
200
My dog Jupiter buys a set of toys for $134.
He also buys a bag of food for $88.
Find the sum of both purchases and check for reasonableness.
134 + 88 = 222
134 is about 130
88 is about 90
130 + 90 = 220
The answer is reasonable because 220 is close to the actual sum.
300
What does it mean to round to the nearest ten?
It means to change the number in the ones place to a zero and leave the tens place the same if the one was 1,2,3, or 4 or change the tens place up a digit if the ones place was 5,6,7,8, or 9.
300
131 + 50 =
181
300
355 - 30 =
325
300
What is 999 rounded to the nearest ten?
1000
300
My dog Jupiter buys a set of toys for $253.
He also buys a bag of food for $38.
Find the sum of both purchases and check for reasonableness.
Write a sentence explaining why the answer is reasonable or isn't.
253 + 38 = 292
253 is about 250
38 is about 40
40 + 250 = 290
The answer is reasonable because 292 is close to 290.
400
What does it mean to estimate?
To estimate means to look at a problem, round the numbers involved and take a guess at the answer.
400
556 + 70 =
626
400
872 - 90 =
772
400
What is 85 rounded to the nearest ten?
90
400
You get a job delivering burritos to teachers. You earn 76 dollars in a month. Your friend works to make the burritos and earns about 82 dollars per month. How much do you both make together? Use estimation to check and WRITE A SENTENCE explaining if your answer is reasonable.
76 + 82 = 158
76 is about 80
82 is about 80
80 + 80 = 160
The answer is reasonable because 158 is about 160.
500
What does it mean for an answer to be reasonable?
A reasonable answer is one that makes sense when compared to the estimation?
500
466 + 300
766
500
643 - 100
543
500
What is 482 rounded to the nearest HUNDRED?
500
500
Ms. Glenn wants to buy movie tickets for the entire class. She needs to estimate how much it will cost to see if the school has the money. She knows that 10 tickets cost $98.
If she want to take 60 students, about how much will it cost?
$98 is about 100.
10 + 10 + 10 + 10 + 10 + 10= 60
10 goes into 60, 6 times.
100 x 6 = 100+100+100+100+100+100 = 600