1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Talja [164]
4 years ago
7

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]4 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.

You might be interested in
Quadrilateral ABCD ​ is inscribed in a circle.
alexdok [17]
When a quadrilateral is inscribed in a circle, the opposite angles are supplementary.

x + 2 + 3x + 6 = 180
4x + 8 = 180
4x = 172
x = 43

Now solve for A
3(43) + 6 = A
129 + 6 = A
135 = A

The measure of angle A is 135 degrees.

Hope this helps =)
7 0
4 years ago
you pick a number between 1,000 and 5,000 then you flip a coin identify if the two events are independent or dependent explain
Lelu [443]
Independent one has nothing to with the other

7 0
3 years ago
Read 2 more answers
Suppose ΔXYZ is given, and you want to construct ΔABC so that the triangles are congruent. Which constructions would guarantee t
bekas [8.4K]

Answer:

A: constructing ΔABC so that AB ≅ XY, BC ≅ YZ, and CA ≅ ZX

C: constructing ΔABC so that AB ≅ XY, CA ≅ ZX, and ∠A ≅ ∠X

Step-by-step explanation:

* Lets revise the ways of constructing a triangle

- There are 3 ways to construct a triangle

# You must have length of one side and measures of two angles which

  are the endpoint of the side

# You must have a length of two sides and the measure of the including

  angle between the two sides

# You must have the length of the 3 sides

* Lets solve the problem

∵ Δ XYZ ≅ Δ ABC

∴ XY = AB , YZ = BC , ZX = CA

∴ m∠ X = m∠ A , m∠ Y = m∠ B , m∠ Z = m∠ C

- To construct Δ ABC You can use:

# The length of the 3 sides

∵ AB ≅ XY , BC ≅ YZ , CA ≅ ZX

∴ constructing ΔABC so that AB ≅ XY, BC ≅ YZ, and CA ≅ ZX ⇒ A

# The length of two sides and the measure of the including angle

∵ AB ≅ XY , CA = ZX

∵ The including angles between the sides are ∠A and ∠X

∴ constructing ΔABC so that AB ≅ XY, CA ≅ ZX, and ∠A ≅ ∠X ⇒ C

# The length of one side and the measures of two angles which are

   the endpoints of the side

∵ CA ≅ ZX

∵ The end points are C , A and Z , X

∴ constructing ΔABC so that CA ≅ ZX, ∠A ≅ ∠X, and ∠C ≅ ∠Z

- But this answer not in the choices

∴ The answer is A and C

4 0
4 years ago
Read 2 more answers
What are all the primes of 52
AleksandrR [38]
<span>52 can be broken down to the following 
2*26 =52
2*(2*13) <---13 x 2=26 x 2=52 
2*2*13 or 2^2*13 <--BOTH mean the same thing :)  </span><span>
</span>
6 0
3 years ago
Please help!!!will get brainliest!
il63 [147K]
Turn the information into coordinate points.

Point = (time, population)

Point 1 = (1985, 45000)
Point 2 = (2004 , 26000)

Find the slope between these points using the formula

( Slope)—> m = (y2 - y1) / (x2 - x1)
26000-45000/2004-1985=-19000/19= -1000
Average rate of change is decrease of 1000 sea lion per year

I hope that helped
6 0
3 years ago
Other questions:
  • Ex 9 va rog mult <br> Dau 20 de puncte.
    5·1 answer
  • . A mason has 7,758 bricks that he needs to share equally among 9 different building sites. How many
    12·2 answers
  • Evaluate integral _C x ds, where C is
    12·1 answer
  • The eggs of birds and other animals come in many different shapes and sizes. Eggs often have a shape that is nearly spherical. W
    6·1 answer
  • Circle O is shown below. The diagram is not drawn to scale? If Angle r is 32, what is angle O?
    5·1 answer
  • What the answer fast
    10·1 answer
  • 24 ounces of vinegar in 60 ounces of oil what is the ratio of oil to vinegar in the salad dressing
    5·1 answer
  • What is 7/8 plus 4/6 equal
    8·1 answer
  • Can you construct a triangle that has side lengths 8 m 10 m and 19 m
    7·1 answer
  • What is the solution to (5d+8)=3(8-d)
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!