Mental Math
Multiplying Whole Numbers and Decimals
Estimating
Multiplying Two Decimals
Multiplying with Zeros
100
4.23 x 1
4.23
100
9.8 x 2
19.6
100
Estimate using rounding or compatible numbers. 9.02 x 80
9 x 80 = 720
100
0.6 x 0.49
.294
100
0.3 x 0.2
0.06
200
0.0867 x 100
8.67
200
34 x 5.3
180.2
200
Estimate using rounding or compatible numbers. 184 x 0.75
200 x 0.8 = 160
200
9.1 x 11.6
105.56
200
6.04 x 0.08
0.4832
300
0.32 x 100
32
300
27.4 x 7
191.8
300
Estimate using rounding or compatible numbers. 0.12 x 5
0.1 x 5 = .5
300
0.28 x 3.7
1.036
300
5.02 x 0.002
0.01004
400
0.001 x 10
0.01
400
170 x 0.003
.51
400
Estimate using rounding or compatible numbers. 25 x 0.37
25 x .4 = 10
400
0.06 x 15
.9
400
3.04 x 0.009
0.02736
500
7.25 x 1,000
7250
500
34,000 x 2.65
What is 90,100
500
Estimate using rounding or compatible numbers. 0.667 x 4
.7 x 4 = 2.8
500
3.14 x 6.2
19.468
500
8.68 x 0.0005
0.00434
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