Homework Comments

Can you…• Show why x •0=k is not true for

nonzero x?

Explain what is wrong:

“50 ÷ 7 is the same as 50 ÷ 10, (which is 5) then because I adding 3 to the divisor I now need to subtract 3: 5 - 3 = 2.”

• Estimate 35 • 49.• Show 3 different ways to find:

35 • 49.• Estimate 27984 ÷ 82. • Show 27984 ÷ 82 using the scaffolding

method.

• 35 • 49 is about 35 • 50. • Think: 30 • 50 = 1500, and 5 • 50 = 250, so

1750.• Methods: rectangular area, lattice

multiplication, Egyptian Duplation, any of the methods used by the kids.

• 27984 ÷ 82: 82 • 1 = 82; 82 • 10 = 820; 82 • 100 = 8,200; 82 • 1000 = 82,000.So, the quotient is between 100 and 1000, and is closer to 100. Now: 8 • 3 = 24, so guess 300.

27984 ÷ 82

• 82 • 1 = 82; 82 • 10 = 820; 82 • 100 = 8,200

82 ) 27984 24600 3384 1640 1744 1640 104 82 22

1 20 20 300

I’m thinking of a number. It is less than 50. When I divide it by 8, I get a remainder of 5. But when I divide it by 7, I get a remainder of 2. Use the manipulatives to find my number.

Do I Understand???• Given: 4 7

X 3 9 4 2 3 1 4 1__ 1 8 3 3

• Question: Without doing any work, what is 30 • 47? How do you know?

Do I Understand?• Given: 208 R 7

18 ) 3751 36

151144

• Question: Without doing any work, what is 200 • 18? How do you know?

Make this true for order of operations

12 ÷ 4 - 2 • 5 = 30

What other values can we get using 12 ÷ 4 - 2 • 5?