Basic Facts
Multiply by 2-digit numbers
Estimating to Multiply/Compatible Numbers
Story Problems
ISTEP+
100
7x8=
56
100
14x10=
140
100
Estimate 67x43
70x40=2,800
100
Cassie picked 12 baskets of apples. Each basket has 60 apples. How many apples did she pick in all?
12x60=720
100
How is using compatible numbers different than estimating/rounding?
Using compatible numbers is similar to rounding. But instead of following the rules of rounding, you use numbers that are close to the actual number and easy to multiply in your head.
200
5x11=
55
200
70x20=
1400
200
Estimate 51x28
50x30=1,500
200
Phoebe draws 18 pictures a day. About how many drawings will she have after 10 days?
ABOUT means estimate! 20x10=200
200
In the problem 24x7, would you get a more accurate answer by rounding or using compatible numbers?
Compatible numbers. When rounding, the problem would be 20x10=200 When using compatible numbers, the problem would be 25x7=175
300
3x9=
27
300
12x40
480
300
Use compatible numbers to find 24x18
25x20=500
300
A table is 24 inches tall. The ceiling is about 6 times higher than the table. About how high is the ceiling?
Estimating: 20x10=200 Compatible Numbers: 25x6=150
300
Round 1,326 to the nearest hundred.
1,300
400
12x7=
84
400
15x30=
450
400
Use compatible numbers to find 26x48
25x50=1,250
400
Ross eats 3 cookies a day. He gives away 20 times as many as he eats. How many cookies does Ross give away?
Ross gives away 60 cookies
400
Sarah and Lisa are doing a bake sale to raise money for a local museum. Sarah baked 14 cakes for the bake sale. Lisa baked 6 cakes. Each cake was sold for $11. How much money did they raise for the museum?
14+6=20 20x11=$220
500
11x12
132
500
25x40
1,000
500
Estimate to find 62x58
60x60=3,600
500
Richard runs an average of 13 miles a day. About how many miles would he have run after 29 days?
About means estimate! 10x30=300
500
Chris paid $500 for his ticket to the Super Bowl. Jack paid three times as much as that. How much did both of them spend combined?
500x3=1500 1500+500=$2,000