Estimating Differences
Estimate by rounding to the nearest ten.
85 - 49 = ?
90 - 50 = 40
Subtract. Then write and solve an equation to check the answer using inverse operations.
300 - 189 = ?
300 - 189 = 111
111 + 189 = 300
763 - 455 = ?
763 - 455 = 308
An artist made 204 picture frames. He sold 75 picture frames to a gift shop. How many picture frames does he have left?
What are you asked to find?
The number of picture frames he has left.
Estimate by rounding to the nearest ten.
36 - 23 = ?
40 - 20 = 20
Subtract. Then write and solve an equation to check the answer using inverse operations.
526 - 388 = ?
526 - 388 = 138
138 + 388 = 526
341 - 124 = ?
341 - 124 = 217
An artist made 204 picture frames. He sold 75 picture frames to a gift shop. How many picture frames does he have left?
What is a word equation to solve the problem?
Number of frames made - number of frames sold = number of frames left
Estimate using front-end estimation.
362 - 219 = ?
300 - 200 = 100
Add. Then write and solve an equation to check the answer using inverse operations.
259 + 242 = ?
259 + 242 = 501
501 - 242 = 259
700 - 256 = ?
700 - 256 = 444
An artist made 204 picture frames. He sold 75 picture frames to a gift shop. How many picture frames does he have left?
What is the answer?
129 picture frames
Estimate by rounding to the nearest hundred.
733 - 195 = ?
700 - 200 = 500
Add. Then write and solve an equation to check the answer using inverse operations.
119 + 693 = ?
119 + 693 = 812
812 - 693 = 119
500 - 368 = ?
500 - 368 = 132
A family played a game during a car trip. They counted things that they saw that were red, green, and blue. They saw 112 red things, 315 green things, and 120 blue things.
How many more green things did they see than red things and blue things combined?
315 - (112 + 120) = 83
Estimate by rounding to the nearest hundred.
498 - 359 = ?
500 - 400 = 100
Subtract. Then write and solve an equation to check the answer using inverse operations.
954 - 159 = ?
954 - 159 = 795
795 + 159 = 954
400 - 287 = ?
400 - 287 = 113
Dan’s grandmother gave him $100. Then he earned $37 babysitting and $22 running errands. Dan wants to know how much money he now has. He added $37 + $22 and got $59. Then he subtracted from $100: $100 - $59 = $41.
What mistake did Dan make? Explain. What is the correct answer?
He subtracted from 100.
He needs to find the total, so he should add. The correct answer is $159.