multiplying by a 2-digit number

multiplying by a 2-digit number

P4

Recall: multiplying by tens

12 x 10 = 120

23 x 10 = 230

468 x 10 = 4680

--> add a zero at the back

Multiple Choice

A possum can have up to 21 babies at one time. Suppose 10 possums had babies all at the same time. How many baby possums could there be?

• 320 possums

• 240 possums

• 110 possums

• 210 possums

23 x 13 =

23 + 23 + 23 + 23 + 23 + 23 + 23 + 23+ 23 + 23 + 23 + 23 + 23 =

So, we split the 13

13 --> 10 + 3

23 x 13 = 23 x 10 + 23 x 3

= 230 + 69

= 299

15 x 75

• = 75 x 15

• = 75 x 10 + 75 x 5

• = 750 + 375

• = 1125

Multiple Choice

Elizabeth is making 22 necklaces. Each necklace has 16 beads. How many beads does she need to make all of the necklaces?

• 154 beads

• 250 beads

• 320 beads

• 352 beads

150 x 12

• = 150 x 10 + 150 x 2

• = 1500 + 300

• = 1800

71 x 27 =

• method 1: 70 x 27 + 27 x 1

• method 2: multiplication frame

• Ans: 1917

Multiple Choice

Mr Teo bought 62 boxes of tiles for his kitchen floor. Each box of tiles cost $45. How much money did Mr. Hans pay for the tiles?

• $450

• $1336

• $2260

• $2790

Multiple Select

567 x 23 can be estimated to

• 500 x 20

• 600 x 20

• 570 x 20

• 560 x 30

Multiple Choice

619 X 80 =

• 49 520

• 50 520

• 39 520

• 59 520

What is the 21st multiple of 17?

• 17 x 21

Multiple Choice

645 x 23 can be estimated to

• 650 x 20

• 640 x 20

• 600 x 20

• 700 x 30

Multiple Select

Select all the number(s) which is a multiple of 2 and has a factor of 21?

• 42

• 14

• 21

• 84

Multiple Select

A number is a multiple of 17 and a factor of 4. Which of these number(s) could be the number? Select all that applies.

• 34

• 48

• 68

• 85

• 136

complete Page 45-46 of workbook.

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