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Multiplying Decimals

Multiplying Decimals. Ms. Mayner. or. Strategy #1. 405 x 59. 405 x 59. 405 x 9. 405 x 50. +. 3. 6. 4. 4. 5. 2. 0. 2. 2. 5. 0. (5 x 4) = 20 Since there are no other numbers to multiply, write down the 20. (5 x 0) + 2 = 2 Write down the 2.

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Multiplying Decimals

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  1. Multiplying Decimals Ms. Mayner

  2. or Strategy #1 405 x 59 405 x 59 405 x 9 405 x 50 + 3 6 4 4 5 2 0 2 2 5 0 (5 x 4) = 20 Since there are no other numbers to multiply, write down the 20. (5 x 0) + 2 = 2 Write down the 2. Zero is a place holder. Put a zero in your answer to hold its place. (9 x 0) + 4 = 4 Write down the 4. 5 x 9 = 45 Put the 5 in the answer and carry the 4 (it’s really 40) to the next place value (tens) 5 x 5 = 25 Put the 5 in the answer and carry the 2 (it’s really 20) to the next place value (tens) (9 x 4) = 36 Since there are no other numbers to multiply, write down the 36.

  3. or Strategy #1 405 X 59 405 x 59 405 x 9 405 x 50 + 3 6 4 4 5 2 0 2 2 5 0 23,895 the final answer is

  4. MULTIPLYING DECIMALS: Things you need to know… • Do not line up the decimal points! • Instead, place the number with more digits on top. • Line up the other number underneath, at the right. • Pretend all decimals are whole numbers until the very end • Only look at the decimals when trying to figure out where to put the decimal point in your answer

  5. Example: 5.63 x 3.7 1 Decimal Places 4 2 5.63 two x 3.7 one 1 1 39 4 1 1 + 16 8 9 0 2 0 . 8 3 1 three

  6. Example: 0.53 x 2.618 2.618 has more digits (4) than 0.53 (3), so it goes on top. 3 4 Decimal Places 1 2 2.618 three x 0.53 two 1 7 8 5 4 13 0 9 0 0 + 0 0 0 0 00 . 1 3 8 7 5 4 five

  7. Try This: 6.5 x 15.3 3 1 2 1 15.3 one x 6.5 one 1 7 6 5 + 9 1 8 0 . 9 9 4 5 two

  8. Homework • Multiplying Decimals Page 47 #1 d-g, 2 a-d, 9 • 2.5 Multiplying Decimals Page 48-49 # 3, 5, 9, 11

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