When you multiply a number by 0.1, which direction do the digits shift?
To the left!
20 x 10 = 2,000. True or False?
False! 20 x 10 = 200
34 x 7 =
238
2.2 x 34 =
74.8
32 x 49 = approximately what when I round?
30 x 50 = 1,500
To the left, two places!
50 x 40 = 200. True or False?
False. 50 x 40 = 2,000
52 x 9 =
468
3.4 x 5.6 =
19.04
Sam estimated his answer to be 4,800 when he multiplied 51 x 39. Is this reasonable?
No. 51 x 39 should be rounded to 50 x 40 = 2,000.
When you multiply a number by 100, which direction do the digits shift?
To the right!
What is 60 x 400?
24,000
6.2 x 3 =
18.6
0.24 x 0.31 =
0.0744
Tony estimated her answer to be 32,000 when she estimated 789 x 41. Is this reasonable?
Yes. 789 x 41 rounds to 800 x 40 = 32,000.
You multiplied a number by .0001. What direction, and how many places did the digits shift?
4 places to the left!
20 x 30 x 40 =
24,000
0.28 x 9 =
2.52
An Atlas Moth has a wingspan of 11 inches. How wide would the wingspans of 73 Atlas Moth's be?
803 inches.
Round and Estimate 37 x 63.
40 x 60 = 2,400
Use shifting patterns, what is 345 x 0.01?
3.45
Which one does not equal 32,000? 80 x 400. 8 x 4,000. 800 x 40. 8,000 x 40.
8,000 x 40.
3.4 x 0.6 =
2.04
Mike wants to save $400 for some new clothes. He makes $22 an hour and worked 19 hours. Did he save enough to reach his goal?
Yes. He saved $418!
Name one place you see decimals every day.
Gas station. Money.