Estimating and Solving Addition Problems

You have 345 apples and you give 123 apples to your friend. How many apples do you have left? Should you estimate or find the exact answer?

• Estimate, because it's easier to calculate quickly.

• Exact answer, because you need to know the precise number of apples left.

• Estimate, because the numbers are too large.

• Exact answer, because estimation is not useful here.

Estimate the sum of 478 and 263 by rounding each number to the nearest hundred.

• 700

• 800

• 900

• 1,000

Calculate the exact sum of 567 and 432 using the standard algorithm.

• 899

• 999

• 1,009

• 1,099

Which of the following expressions are equal?

You have 800 marbles. You lost 150 marbles and then found 75 marbles. How many marbles do you have now?

• 625

• 725

• 675

• 750

• Estimate, because you only need to know if you have about enough.

• Exact answer, because you need to know precisely if you have enough.

• Estimate, because the numbers are close.

• Exact answer, because estimation is not useful here.

Estimate the difference between 732 and 489 by rounding each number to the nearest ten.

• 230

• 240

• 250

• 260

Find the exact difference between 876 and 543 using the standard algorithm.

• 323

• 333

• 343

• 353

Which of the following expressions are not equal?

You have 950 stickers. You give 300 stickers to your friend and then buy 150 more. How many stickers do you have now?

• 800

• 700

• 750

• 850