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Discovering Decimals in the Wonderful World of Mathematics

Learn about decimal numbers, converting fractions, comparing and operating with decimals, and practical applications in daily life. Explore the concept of wholes, decimal points, and operations involving decimals through various examples and homework exercises.

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Discovering Decimals in the Wonderful World of Mathematics

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  1. Wonderful world of Decimals 

  2. What is a decimal number? • Think about money A decimal is a part of a whole.

  3. 1 dollar and 4 dimes • 1.40$ Part of the whole Whole

  4. On a number line 1 4 0

  5. Converting from fraction to Decimal • THERE ARE 2 WAYS • 1) You can write the fraction with a denominator that is a power of 10. • (10,100,1000….) Denominator is the bottom number of a fraction • Ex • =

  6. Step 2 • Than move your decimal place one spot to the left, because the 10 has 1 zero. • 6. 0 .6

  7. More examples How many decimal points will I move to the left? 245.

  8. Look at money again. • It takes 10 dimes to make 1 dollar. So 1 dime is 1 tenth of the whole

  9. It takes 100 pennies to make 1 dollar A penny is one hundredth of a dollar

  10. Second way • Divide the numerator by the denominator. • 7÷16 • =0.4375

  11. Express the following mixed fraction as a decimal • 2 =2. a decimal • 2÷3 =0.66 • 2.66

  12. Homework • Pg 90#15,16,17 • Pg 91# 18,19,20

  13. Comparing decimal numbers • If 2 decimal numbers have different wholes • Ex. • 4.56 and 7.89 • The one with the larger whole is bigger.

  14. Comparing decimal numbers • If the 2 numbers have the same whole but different decimal numbers. • 6.54 and 6.43 • The one with the larger tenth digit is bigger

  15. Adding and subtracting decimals • Example : 235.7 +18.276 • 1) Write digits with the same position under each other and line up the decimal point. • 235.7 • + 18.276 • 2) Add or (subtract) the numbers ignoring the decimal point. • 235.7 • + 18.276

  16. Adding and subtracting decimals • 3) Place the decimal point directly under the decimal of the other numbers. • 2 3 5 .7 • + 1 8 .2 7 6 • 2 5 3. 976

  17. Homework Pg 94#1-5

  18. Word Problem • You are going shopping for groceries and you want to save as much money as possible. Here are the prices at 2 stores: Which Grocery store would give you the best deal overall and how much would it cost?

  19. Pg 95 • #7-11

  20. Multiplication and division of decimals • 1) When multiplying by a power of ten (10,100,1000…) Move the decimal one place to the right for every zero Example: 3.45 X100 3.45 =345.00

  21. Multplication with decimal numbers Move the decimal one place to the Left for every zero. 003.45 =.00345

  22. Multiplication • For all other numbers, • 1) Multiply them as if they were not decimal numbers. • 35.18 • X 4.7 • 24 626 • + 1 40 720 • 1 65 346 • 2) Count the number of decimal places in the 2 numbers • we have 3. • 3) Put the decimal place in the result so it is same as the total of the 2 numbers.

  23. Homework • Pg 96 • ALL • Pg 97 #3 & 4

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