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Maths Book 6 Decimals Part 2

Maths Book 6 Decimals Part 2. A maths programme to teach maths' skills for the primary years. Dennis Sparrow Educational Psychologist. Lesson 20: Dividing Decimals by 10, 100, 1000. Let’s learn how to divide by 1, 10, 100, 1000 an easier way.

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Maths Book 6 Decimals Part 2

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  1. Maths Book 6 Decimals Part 2 A maths programme to teach maths' skills for the primary years. Dennis Sparrow Educational Psychologist

  2. Lesson 20: Dividing Decimals by 10, 100, 1000 Let’s learn how to divide by 1, 10, 100, 1000 an easier way. Rule 1. when you divide by 1, the decimal point does not move. The number is unchanged. Rule 2. when you divide by 10, the decimal point moves ONE place to the LEFT. Rule 3. when you divide by 100, the decimal point moves TWO places to the LEFT. Rule 4. when you divide by 1000, the decimal point moves THREE places to the LEFT. .

  3. Lesson 20: Dividing Decimals by 10, 100, 1000 Another Rule. when you divide by 10, 100, 1000, the number gets smaller. example 1: 115.4 ÷ 10 = 11.54 This can also be written as: Exercise 24: Divide the following decimals by. 1 10 100 1000 Add zeros in front of the number if needed: 492.1 5678.3 54.73 6775.3

  4. 3. 21 +0. 24 3. 45 Lesson 21: Adding and Subtracting Decimals and Rounding Let’s learn how to add and subtract decimals and round off the answer. Rule. The decimal point in the answer, when adding and subtracting, must be directly under the decimal point in the problem. example: Now learn how to round this to tenths.

  5. 3. 21 +0. 24 3. 45 Lesson 21: Adding and Subtracting Decimals and Rounding Remember this rule: Rule: If the digit to the right of the number being rounded is 5 or greater, add 1 to the number in the Rounded Place. Round this to tenths: The digit to the right of the number being rounded (.4) is equal to 5, therefore add 1 to the 4. Round 3.45to tenths = 3.5

  6. Lesson 21: Adding and Subtracting Decimals and Rounding Exercise 25: (a) Add or subtract the following. (b) Align the decimal points first. (c) Round each answer to tenths: .36 3.62 15.564 4.31 +1.68+16.78-6.672+5.57 7.98 5.74 54.897 3.21 -4.43+10.85+35.32-0.4

  7. Lesson 22: Multiplying Decimals and Rounding Remember the rule: When multiplying 2 or more decimals, we count the places AFTER decimal point in both (or more) numbers. Exercise 26: Multiply and round to tenths:

  8. Lesson 23: Dividing Mixed Numbers New Rule: We do NOT divide by a decimal, we must change this number to a whole number first. example 1: 1. Let’s learn how to divide by numbers that are not whole numbers. 2. I’ll use fractions to rewrite the problem. 3. Dividing by a decimal is not done, so I will change .5 to a whole number.

  9. Lesson 23: Dividing Mixed Numbers 4. Remember a number is a whole number when there are no digits after the decimal point. 5. I will multiply .5 by 10 (because .5 is a 5 tenths) to end with 5. 6. I don’t want to change the value of the fraction, so I must multiply the fraction by a fraction equivalent to 1 (i.e. 10/10). 7. I will multiply by 10/10 to find the numerator of the answer. 8. Now complete the division to find the answer.

  10. Lesson 23: Dividing Mixed Numbers example 2: 1. I will multiply .60 by 100 (because .60 is 60 hundredths) to end with 60. 2. I don’t want to change the value of the fraction, so I must multiply the fraction by a fraction equivalent to 1 (100/100). 3. Now complete the division to find the answer. 4. So 2.40 = 4 .60

  11. Lesson 24: Dividing Mixed Numbers, Rounding the Answer Reminder Rule: Line up the decimal point in the answer with the one in the problem. example 1: 1. Divide as you would any long division problem. Line up the decimals. 2. The answer is 1.110 (i.e. to thousandths). This is enough as we want to round to tenths.

  12. Lesson 24: Dividing Mixed Numbers, Rounding the Answer example 1(continued): 3. Round 1.110 to tenths. 4. The digit just to the right of the tenth (1) is less than 5 so the digit in the tenth position remains the same. 5. The answer is: 1.110 = 1.1 Rounded to tenths.

  13. Lesson 25: Changing Fractions to Decimals Rule: To change a fraction to a decimal, divide the numerator by the denominator. example 1: 1. Turn 1 (the numerator) into a decimal by adding a decimal point and 2 zeroes. 2. Divide the fraction as you would any division problem, but line up the decimal points. 4. Round the answer to tenths.

  14. Lesson 26: Changing Decimals to Fractions example 1: 3.75 1. The number to the left of the decimal point is a whole number. 2. The number to the right of the decimal point is a decimal. 3. 3 is the whole number, so we have 3 and 75/100. 4. So the decimal says 75 hundredths. 5. In this problem we can simplify the fraction (25 is the Greatest Common Factor of 75 and 100). 6. So: 7. And:

  15. Lesson 26: Changing Decimals to Fractions Exercise 25:Convert the following decimals to fractions. Simplify where you can:

  16. Lesson 26: Changing Decimals to Fractions Exercise 25:Convert the following decimals to fractions. Simplify where you can:

  17. Lesson 26: Changing Decimals to Fractions Exercise 25:Convert the following decimals to fractions. Simplify where you can:

  18. Now go to Lesson 1 Book 7 Percent and Ratios

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