Mental Math and Estimation

Mental Addition

100

Find 36 + 41 mentally.

77

200

Find 48 + 11 mentally.

59

300

Find 16 + 22 mentally.

38

400

Find 36 + 46 mentally

82

500

Find 45 + 46 mentally.

91.

Mental Subtraction

100

Find 55-23 mentally.

32

200

Find 88 - 22 mentally.

66

300

Find 92 - 51 mentally.

41

400

Find 72-37 mentally.

35

500

Find 92-33 mentally.

59

More Mental Addition

100

Find 39 + 96 mentally.

135

200

Find 98 + 21 mentally.

119

300

Find 37 + 99 Mentally.

136

400

Find 97 + 98 mentally.

195

500

Find 99 + 99 mentally

198

Round to the Nearest Hundred

100

Round to the nearest hundred.

122

100

200

Round to the nearest hundred.

378

400

300

Round each addend to the nearest hundred, then add.

421 + 289

700

400

Round to the nearest hundred.

2345

2300

500

Round each addend to the nearest hundred, then add.

3420 + 2820.

6200

Front-End Estimation

100

What is the leading digit in 365?

3

200

What is 952 using front-end estimation?

900

300

What is 765 using front-end estimation?

700

400

Use front-end estimation for each addend, then add.

879 + 167.

900

500

Use front-end estimation for each addend, then add.

1789 + 8029

9000.