True or False
When multiplying decimals you drop the decimal point where it is, since everything is lined up by place value.
False
To place the decimal point into the product you count the number of place values in the expression. It is not lined up by place value.
Estimate:
2.3 x 5.2
2 x 5 = 10
2.3 x 5.2 is about 10
3 x 0.26
0.78
0.36 x 24
8.64
Each tablet costs $245.75. A school buys 6 tablets. If the school pays with $1,500, how much change should they receive?
$245.75 x 6 = $1,474.50
$1,500 - $1,474.50 = $25.50
The school will receive $25.50 in change.
Money values have only two decimal place values.
True
5,625 x 21
118,125
7 x 2.56
17.92
2.1 x 56
117.6
One hotel room costs $189.60 per night.
A family stays for 4 nights. If the family also pays $125.40 in taxes and fees, what is the final total?
$189.60 x 4 = $758.40
$758.40 + $125.40 = $883.80
The family will pay $883.80
When estimating decimal products you solve then round the product to the nearest whole number.
False
When estimating decimal products you round the factors to the nearest whole number then solve.
Estimate:
14.5 x 3.6
15 x 4 = 60
14.5 x 3.6 is about 60
9 x 1.365
12.285
18 x 0.92
16.56
A roll of flooring costs $318.45. A contractor buys 7 rolls. If the contractor’s budget is $2,500, how much money remains after the purchase?
$318.45 x 7 = $2,229.15
$2,500 - $2,229.15 = 270.85
4.2 x 2 = 2.4 x 4
False
4.2 x 2 = 8.4
2.4 x 4 = 9.6
8.4<9.6
4.2 x 2 < 2.4 x 4
588 x 98
57,624
5 x 10.25
51.25
64 x 2.23
66.23
Each violin costs $475.80. A music school buys 8 violins. If the school has $4,000 set aside, will they have enough money? If yes, how much will be left over? If not, how much more is needed?
$475.80 x 8 = $3,806.40
$4,000 - $3,806.40 = $193.60
The school will have $193.60 in their budget.
100 x 3.4 = 0.034
False:
100 x 3.4 = 340
When multiplying decimals by powers of 10 you count the zeros and move the decimal that many places to the right.
Estimate
6.98 x 124.3
7 x 124 = 868
6.98 x 124.3 is about 868
6 x 7.85
47.1
100 x 2.36
236
Each gift basket sells for $129.95. A club sells 9 gift baskets. If the club spends $ 362.25 on products and another $112.50 on supplies, how much profit does the club make?
$129.95 x 9 = $1,169.55
$ 362.25 + $112.50 = $474.75
$1,169.55 - $474.75 = $694.80
The club makes $694.80 in profit.