Open Query 19

course Mth151

019. `query 19

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Question: `q query 4.2.6 53812 in expanded form.

What is 53812 in expanded form?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution: (5*10^4)+(3*10^3)+(8*10^2)+(1*10^1)+(2*10^0) = 53812

confidence rating #$&* 2

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Given Solution:

2 means 2 * 10^0

1 means 1 * 10^1

8 means 8 * 10^2

3 means 3 * 10^3

5 means 5 * 10^4

Thus the number 53812 means

(5*10^4)+(3*10^3)+(8*10^2)+(1*10^1)+(2*10^0).

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Self-critique (if necessary):OK

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Self-critique rating #$&*2

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Question: `q query 4.2.20 536 + 279 in expanded notation

Write 536 + 279 in expanded notation.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution: 5 * 10^2 + 3 * 10^1 + 6 * 10^0 +

2 * 10^2 + 7 * 10^1 + 9 * 10^0

9 * 10^2 + 1 * 10^1 + 5 * 10^0. = 915

confidence rating #$&*2

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Given Solution:

`a** We write this sum as

5 * 10^2 + 3 * 10^1 + 6 * 10^0 +

2 * 10^2 + 7 * 10^1 + 9 * 10^0

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8 * 10^2 + 10* 10^1 + 15* 10^0. Since 10 * 10^1 = 10^2 we can write this as

9 * 10^2 + 0 * 10^1 + 15 * 10^0.

Since 15 * 10^0 = 10 * 10^0 + 5 * 10^0 = 10^1 + 5 * 10^0 we rewrite this as

9 * 10^2 + 1 * 10^1 + 5 * 10^0.

This result is expressed in our place-value system as

915. **

STUDENT QUESTION:

When adding the 6*10^0 and the 9*10^0 I don�t carry the one like in regular math?

INSTRUCTOR RESPONSE:

We're not applying the rules for addition as we all learned them in elementary school, but reasoning our results out from the more basic perspective of a place-value system.

6 * 10^0 + 9 * 10^0 = 15 * 10^0.

15 * 10^0 means 10 * 10^0 + 5 * 10^0, and since 10 * 10^0 = 10^1 we conclude that our original expression 15 * 10^0 is equal to 1 * 10^1 + 5 * 10^0.

This is the reason you 'carry the 1'.

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Self-critique (if necessary):OK

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Self-critique rating #$&*2

&#Good work. See my notes and let me know if you have questions. &#