Multiplying by 10's
Mental Math to Multiply
Rounding to Estimate
Compatible Numbers
Fill in the Blank
100

10 X 12 =

120

100

20 X 20 =

400

100

31 X 12=

300

100

23 X 12= 

250

100

How many zeros are in the product 60 X 90?

two zeros
200

20 X 18 =

360
200

50 X 10= 

500

200

28 X 17 = 

600

200

24 X 31=

750

200

To find 90 X 30, you multiply ________ and _______.

9 times 3

300

30 X 34 =

1,020

300

40 X 40= 

1,600

300

46 X 13 =

500

300

26 X 42= 

1,000

300

63 is close to _______.

60

400

40 X 16= 

640

400

30 X 80=

2,400

400

38 X 36 =

1,600

400

24 X 61= 

1,500

400

To estimate we could round 24 to ______.

25

500

70 X 35=

2,450

500

70 X 60=

4,200

500

62 X 82 =

4,800

500

26 X 48=

1,250

500

Mark estimates 67 X 36 to 70 X 40, will his estimate be bigger or less than the actual answer?

The answer will be greater because he rounded up.