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3 years ago

How many 7 digit phone numbers (using digit 0 to 9)can be formed if I can't be the first digit

Mathematics

1 answer:

JulijaS [17]3 years ago

4 0

It depends if the number can start with zero and if digits can repeat.

If digits can repeat and it can start with zero than there are 10 options for every digit so the answer is 10**7, or 10000000.

If it can’t start with zero but numbers can repeat, than there are 9 options for the first number and 10 for every other number. So 9 * 10**6, or 9000000.

If it can start with zero but no numbers can repeat than each digit has one less options than the one before it because one number has been used. so 10 * 9 * 8 * 7 * 6 * 5 * 4, or 604800.

If numbers can’t be repeated ant the first digit can’t be zero than the first 2 digits have 9 options, the first is anything but zero the second is zero plus the remaining 8 digits that aren’t zero that haven’t been used so 9 * 9 * 8 * 7 * 6 * 5 * 4, or 544320.

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3 years ago

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50 points! Someone actually help instead of putting random answers! Random answers will be reported

In-s [12.5K]

If you only want to see the way i do it to get the answer without seeing my explanation ignore sentences with symbol '#'

<h2>Answer</h2>

•Pic on the left

x = 8.36

y = 140.18°

• Pic on the right

x = 110°

• This one for the pic on the left

#Since the total degree of a triangle is 180° and one of the side known 90° (L) so the rest must be 90° (180° - 90° = 90°)

#known that the other side of triangle degree is (5x - 2)° and 6x° so... u can find the x! :D

90 = (5x - 2) + 6x

90 = 11x - 2

90 + 2 = 11x

92 = 11x

x = 92 : 11

x = 8.36 (2 decimal places)

#Now you know the x, you can now find the degree

#degree of (5x - 2)

5x - 2 =

5(8.36) - 2 =

41.81 - 2 = 39.81

#Since the y° is in the other side of the line of degre 39.81°, you can find it by minus it with 180° (straight line with no degree is 180°)

180° - 39.81° = 140.18

•This one for the pic on the right

#Lol this one is easy. I already told you before that the straight line degree is 180° and you can find one of the side if you know one of the degree side, so you can find it.

# Also as i said before, total triangle degree is 360°

#Find the degree of the other side of x° (only can find the degree of other side x because its inside the triangle)

Degree = 180° - 80° - 30° = 70°

#Now you can get x

x = 180° - 70° = 110°

<h2>For moderators that see this</h2>

#Moderators please don't be mean, dont delete my answers just for approval from your senior or just to get the biggest moderation daily rank. This answer is long, how can you just instanly delete it? :(

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2 years ago

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jolli1 [7]

Answer:

Henry is short of gravel

Step-by-step explanation:

Here, we are to identify which of the ingredients Henry is short of.

To identify this ingredient, what is needed to be done is to share the 180kg of concrete appropriately to get which of the material does not meet its ratio and thus allowing us know which is insufficient.

The total ratio is 1 + 4 + 7 = 12

For cement, we have ;

1/12 * 180 = 15 kg

For sand, we have

4/12 * 180 = 60kg

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Answer:

Step-by-step explanation:

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P = Present value

R = interest rate

N = number of years

m = number of compounding

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Svetradugi [14.3K]

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Steps:
Apply absolute rule: |a| = a, a >/ 0
|20| = 20
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Apply absolute rule: |a| = a, a >/ 0
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Refine
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Hope this helps you! (:
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