Multiplying by 10 and 100
Multiplying by hundreds
Breaking Apart
Rounding to Estimate
Random
100
8x10
80
100
2x700
1,400
100
4x36
4x30+4x6=120+24=144
100
117x4
120x4--480
100
A toy costs $132. You pay with $150. What's your change?
$18
200
7x100
700
200
7x50
350
200
6x23
6x20+6x3=120+18=138
200
46x5
50x5--250
200
75x8
80x8--640
300
5x100
500
300
60x8
480
300
5x127
5x100+5x20+5x7=500+100+35=635
300
44x8
40x8--320
300
How many miles away from the Earth is the Sun?
93 million miles away
400
40x100
4,000
400
800x5
4,000
400
4x131
4x100+4x30+4x1=400+120+4=524
400
303x5
300x5--1,500
400
Alex's house is 394 miles from Columbus. If Alex makes 5 ONE WAY trips from his house to Columbus, how many miles will he travel?
1,970 miles
500
300x100
30,000
500
600x50
30,000
500
5x325
5x300+5x20+5x5=1500+100+25=1625
500
527x8
500x8--4,000
500
Maria knows that there are 24 hours in one day and 7 days in a week. she said there are 158 hours in one week. Is her answer reasonable?
yes. 7x20=140 and her answer is close enough to 140.
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