STILLWATER CROSSING · THE COURSE NOTES · BRIDGE MATH 5/6

Week 30 · More Multiplying with Decimals

This week

Lessons 141, 142, 143, 144, & 145

Papers

Quiz 14 in class · Last test graded and signed at home

Method

No calculators, ever · show every step

Instructional notes

More on Multiplying with Decimals To multiply with decimals: • Multiply as usual, ignoring decimals

• Count total decimal places in all factors • If the product has fewer digits than decimal places

needed, add zeros to the left • Place the decimal point

Example

Multiply.

Practice

Multiply.

0.07 × 0.5 = 0.035 0.003 × 7 = 0.021

0.12 × 0.4 = 0.048 0.08 × 0.09 = 0.0072

Instructional notes

Division with Decimal Divisors

To divide when the divisor is a decimal:

• Shift the decimal in the divisor right to make a whole number • Place a caret where the decimal should be • Shift the decimal in the dividend the same number of

places to the right • Annex zeros as needed

• Place a caret where the decimal should be

• Divide moving the decimal point up into the quotient

Example

Divide.

Practice

Divide. 24.6 ÷16.4 = 1.5 132.5 ÷ 0.005 = 26,500

Instructional notes

Ratio: shows the relationship between 2 numbers

Antecedent: first number Can be written 3 to 7 Consequent: second number 3 3:7 or 7

Reduce to lowest terms 5 = 15 3 1

4 to 6 = 2 to 3 7:14 = 1:2

Improper fractions should not be 7 3 15 to 1 12:5 changed

Example

Missy knew 14 out of the 105 songs played on the radio. Express the ratio of known to played songs in three ways.

Last month at the animal shelter there were 28 dogs, 4 bunnies and 7 cats.

What is the ratio of bunnies to dogs? 1 4 to 28 = 1 to 7 or 1:7 or 7 1 There were as many bunnies as dogs. 7

There were 4 times as many dogs as cats.

Practice

Mr. Poplin has a bag of balls in his classroom. There are 12 red balls, 6 blue balls, and 42 yellow balls in the bag.

Write the ratio of red to yellow balls three ways. 2 2 to 7 2:7 and 7 Write the ratio of blue to non-blue balls three ways. 1 1 to 9 1:9 and 9 There are 7 times as many yellow balls as blue balls.

1 There are as many red balls as non-red balls. 4

✍ In your own words

what are three concepts that you could ask your teacher to include in the end of year review? Answers will vary.

Homework this week

Work-text	Lesson 141	Lesson 142	Lesson 143	Lesson 144	Lesson 145
Speed drill	141	142	143	145

Terms on the record

Term	Meaning
more multiplying with decimals	More on Multiplying with Decimals

STILLWATER CROSSING // BRIDGE MATH // PENUMBRA · steady on