Add and Subtract Tens Mentally

A store had 53 watches. It sold 30 of them. How many watches are left?

• 23

• 20

• 24

10, 20, 30, 40, ..............................

• 80, 90, 100, 110

• 50, 60, 70, 80

• 30, 40, 50, 60

If you mentally subtract 10 from the number below, what would the total be? 

405 

• 305

• 395

• 400

• 415

What is 10 MORE than 43?

• 53

• 57

• 23

• 5

What is 10 MORE than 10?

• 30

• 0

• 20

• 2

20-8

• 11

• 12

• 13

• 14

Use the sequence below to answer questions 16 and 17. 

 

Look at this counting sequence:  

528, 518, 508, 498, 488 

How are the numbers changing? 

• 90

• 70

• 50

• 60

• 48

• 58

• 68

• 28