Ch. 3 Test Review

Estimate by rounding to the nearest 10 or 100

100

85-49=

90-50=40

200

36-23=

40-20=20

300

733-195=

700-200=500

400

498-359=

500-400=100

500

832-241=

800-200=600

Front-end Estimation

100

362-219=

300-200=100

200

812-284=

800-200=600

300

658-345=

600-300=300

400

978-768=

900-700=200

500

898-165=

800-100=700

Subtract using partial differences

100

Find 627-565

627-500=?

127-20=?

107-40=?

67-5=?

127,107,67,62

200

Find 383-325

383-300=?

83-20=?

63-3=?

60-2=?

83,63,60,58

300

Find 749-492

749-400=?

349-40=?

309-50=?

259-2=?

349,309,259,257

400

Find 430-342=

430-300=130

130-30=100

100-10=90

90-2=88

500

Find 805-698=

805-600=205

205-90=115

115-5=110

110-3=107

Align and Subtract

100

250-142=

108

200

903-241=

662

300

420-161=

259

400

700-256=

444

500

800-193=

607

Align, subtract, and check with addition

100

341-124=

300-100=200

341-124=217

124+217=341

200

532-235=

500-200=300

532-235=297

235+297=532

300

954-159=

1000-200=800

954-159=795

795+159=954

400

526-388=

500-400=100

526-388=138

138+388=526

500

800-657=

800-700=100

800-657=143

143+657=800