Adding/Subtracting Decimals
What do you need to do when adding and subtracting decimals?
Line up the decimals.
What do you do when multiplying decimals?
Stack the numbers as you would normally do to multiply whole numbers. Then count up the decimal place values to know where to place the decimal.
What do you need to do when multiplying by a mixed number?
You need to change the mixed number to a fraction by multiplying the whole number by the denominator and adding the numerator.
What do you need to do when dividing fractions?
You multiply by the reciprocal.
Keep the first fraction
Change the sign to multiplication
Flip the second fraction
Anna's running time for a race was 23.1 seconds. Another runner's time was 5.86 seconds faster. What was the other runner's time?
17.24 seconds
Solve. 5.9 + 2.7 =
8.6
23.12
Solve. 5/7 x 7/9 =
5/9
Solve. 6 ÷ 2/3 =
9
The wings of some hummingbirds beat 52 times per second when hovering. If a hummingbird hovers for 35.5 seconds, how many times do its wings beat?
1,846 times
1.06
What do you do when dividing a decimal by another decimal?
You need to move the decimal of the divisor to get a whole number and then move the decimal of the dividend the same number of places.
Solve. 3/4 x 8 1/2 =
6 3/8
Solve. 3/5 ÷ 2 =
3/10
A lizard can eat 45 ants per minute. How long would it take the lizard to eat 1,080 ants?
24 minutes
6.985
Solve. 5.3 ÷ 0.2 =
26.5
Solve. 5/6 x 9/10 =
3/4
Solve. 4/9 ÷ 2/3 =
2/3
The world's smallest gecko is 3/4 inch long. An adult male Western Branded Gecko is 7 1/3 times as long. How long is the Western Branded Gecko?
5 1/2 inches
Solve. 46.91 - 28.7 =
18.21
Solve. 52.056 ÷ 7.23 =
7.2
Solve. 2 1/6 x 4 1/2 =
9 3/4
Solve. 2 1/3 ÷ 1 1/3 =
1 3/4
A waitress pours 3/4 gallon of orange juice equally into 5 pitchers. What fraction of a gallon of orange juice is in each pitcher?
3/20 gallon