Equations
What number is missing from the equation below?
57 + __ = 57
0
Bonus question: What property is this an example of?
Round 554 to the nearest hundred
600
What is estimating and why do we use it?
It is an approximate calculation used when we do not need to find the actual answer.
What strategy do we use addition for to check our answers?
Inverse operations
Solve 342 - 123
Use any way you choose
342 - 123 = 219
What property is this?
30 + 57 = 57 + 30
commutative property
Round 554 to the nearest ten.
550
Estimate 647 + 210 by rounding to the nearest hundred.
600 + 200 = 800
345 - 234 = 111
How can I use inverse operations to check my work?
11 + 234 = 345
Solve 447 + 238
Solve it any way you choose
447 + 238 = 685
Is this equation true?
43 + (57 + 4) = (43 + 57) + 4
Yes
Bonus: What property is this?
Create your own number to round to the nearest ten and the nearest hundred
Be creative :)
Estimate 534 - 321 by rounding to the nearest ten.
530 - 320 = 210
345 - 230 = 115
230 + ___ = 345
What number is missing from the addition equation to check our work?
115
Solve 654 - 335 using the stacking method
654 - 335 = 319
Which of these equations are true? There can be more than one answer.
a. (354 + 7) + 432 = 354 + (7 + 432)
b. 35 + 0 = 38
c. 378 + 993 = 993 + 378
A and C
Round these numbers to the nearest hundred:
a. 543
b. 789
c. 351
a. 500
b. 800
c. 400
Lincoln invited 234 people to his birthday bash. So far, only 103 people have arrived. How can we use estimation to figure out about how many more people still need to arrive?
234 --> 230
103 --> 100
230 - 100 = 130
Bonus question: Is there another possible answer?
Solve 752 - 437 =
Now use inverse operations to check your work.
answer: 315
inverse operation: 315 + 437 = 752
Solve 324 + 543 using the expanded method
300 + 20 + 4 + 500 + 40 + 3 = 867
Is this equation true? Why or why not?
537 + (432 + 57) = (537 + 432) + 52
No, because the numbers on each side are different.
Round these numbers to the nearest ten:
a. 898
b. 521
c. 762
a. 900
b. 520
c. 760
Sarah received 221 valentines on Valentine's day before 1 pm. After 1 pm, she received 126 more. Estimate how many total valentines she received by rounding to the nearest ten.
220 + 130 = 350 valentines
Willa completed the problem 987 - 729 and got the answer 257. Is her answer correct? How can we use inverse operations to check it?
No, the answer is 258 because 257 + 729 = 987. We need one more in the ones place for the answer to be correct.
Solve 632 - 457 using regrouping
632 - 457 = 175