4th grade math ( Chapter 1 )

4th grade Go math

Chapster 1

Multiplying 2-digit numbers

• Multiplying by 10's

• Estimate products

• Box method

• Partial products (break it up)

• Regrouping (old school)

Multiplying by 10's

When we're multiplying by tens we can focus on multiplying the first digits, and then slap on the zeros after.

64 x 10 = 640

23 x 100 += 2,300

We can also do this if both digits end in zero

60 x 20 = 1,200

30 x 50 =1,500

Or, if just one ends with zero

12 x 20 = 240

12 x 30 =510

Multiple Select

50 x 50 = 2,500

• True

• False

Multiple Select

60 x 30 = 180

• true

• false

Estimate Products

When we estimate products we round them each of the two factors, and then we multiply them.

24 x 38

20 x 40

800

Multiple Select

Estimate the product 88 x 51 =

• 4,000

• 4,488

• 4,500

Multiple Select

Estimate the products 29 x 32 =

• 928

• 600

• 900