Unit 1

subtract

100

31-22=

9

200

57-45=

12

300

80-67=

13

400

123-89=

34

500

704-356=

348

add

100

32+66=

98

200

135+67=

202

300

356+234=

590

400

567+456=

1,023

500

598+321=

919

vocab

100

An ___________ is a number close to the an exact amount.

Estimate 

200

The ___________________________ states that you can add two or more numbers in any order and get the same sum.

Commutative Property 

300

The _____________________________ states that you can group addends in different ways and still get the same sum.

Associative Property 

400

The answer to an addition problem 

Sum

500

The answer to a subtraction problem 

Difference 

estimate

100

Estimate then add: 

34 + 22=

30+20= 50

200

Estimate then add: 

67+55=

70+60= 130

300

Estimate then add:

456+321=

500+300=800

400

Estimate then subtract:

89-34=

90-30=60

500

Estimate then subtract:

467-222= 

500-200=300

rounding

100

Round to the nearest hundreds:

456

500

200

Round to the nearest hundred:

745

700

300

Round to the nearest ten:

678

680

400

Round to the nearest ten

123

120

500

Round to the nearest thousands:

1568

2000