Show:
Estimating and Mental Math
Addition
Subtraction
Missing in the Middle
100

Round each number to the nearest ten and estimate the sum of 395 and 41.

395 + 41 ≈ 440

100

43,193 + 12,105

43,193 + 12,105 = 55,298

100

487,287 - 15,254

487,287 - 15,254 = 472,033

100

112 + _______ = 4,298

4,186
200

Round each number to the nearest hundred and estimate the difference of 890 and 112.

890 - 112 ≈ 800

200

82,391 + 39,689

82,391 + 39,689 = 122,080

200

130,402 - 29,682

130,402 - 29,682 = 100,720

200

10,000 = 7,291 + _______

2,709

300

Round each number to the nearest thousand and estimate the sum of 13,932 and 9,930.

13,932 + 9,930 ≈ 24,000

300

81,049 + 13,239 + 16,575 

81,049 + 13,239 + 16,575 = 110,863

300

60,000 - 6,767

60,000 - 6,767 = 53,233

300

56,193 - ______ = 20,349

35,844

400

Round each number to the nearest thousand and estimate the difference of 29,891 - 15,025.

29,891 - 15,025 ≈ 15,000

400

A teacher taught 4,201 students last year and 599 students this year. How many students did they teach altogether?

They taught 4,800 students altogether.

400

14,000 - 4,999

14,000 - 4,999 = 9,001

400

438,650 - ______ = 71,576

367,074

500

Round each number to the nearest ten thousand and estimate the sum of 143,192 + 67,304 + 9,949.

143,192 + 67,304 + 9,949 ≈ 220,000

500
Grace paid $1,193 for a bike and $250 more for a skateboard. How much did she pay for both the bike and the skateboard?

Grace paid $2,636 altogether.

500

An upright piano costs $9,394 less than a grand piano. A grand piano costs $20,000. How much do both pianos cost together?

Both pianos cost $30,606 altogether.