Adding Subtracting Mentally

Match the following:

• 405

• 277 + 10

• 287

• 395 + 10

• 120

• 199 + 100

• 299

• 278 + 100

• 378

• 5 tens + 7 tens

555 + 10

676 - 10

843 + 100

234 - 100

555 + 10 + 100

999 -10 -100

Mentally adding/subtracting 10s and 100s is

• Super Easy

• Easy

• Somewhat Hard

• Very Hard

2000 + 100 + 10

True or False: The commutative property of addition states that changing the order of the numbers being added does not change the sum.

• True

• The commutative property of addition only applies to odd numbers

• The commutative property of addition only applies to even numbers

• False