Skip to main content

What are the prime numbers between 70 and 100?

By
by seeing the prime number table we know that 25 prime numbers are existing in between 1 to 100
the following table explains


Prime numbers

1-25
2,3,5,7,11,13,17,19,23
9
26-50
29,31,37,41,43,47
6
51-75
53,59,71,73,61,67
6
75-100
79,83,89,97
4
  in the above table shows that from 1 to 25 numbers there are 9 prime numbers
similarly from 25 to 50 there are 6 prime numbers are there.
like wise from 51-75 there are 6 prime numbers and from 75 to 100 there are 4 prime numbers there.

by observing the above tables the the following questions can ask.

1 . What are the prime numbers between 20 and 50?
   Ans:prime numbers : 23,29.31,37,41,43,47
          since there are 7 prime numbers are there between 20 and 50.

2. How many prime numbers are between 30 and 50?
    Ans:prime numbers: 31,37,41,43,47
           since there are 5 prime numbers are there between 30 and 50.

3.What are the prime numbers between 70 and 100?
   Ans: prime numbers: 71,73,79,83,89,97
           there are six prime numbers are there between 70 and 100.
    
      

Comments

Post a Comment

Popular posts from this blog

average of first 100 odd numbers

By
  Odd  numbers are 1,3,5,7,9,…. Average = sum of elements/  no  of elments Now we will see the sum of elements: Sum of first 2 odd  numbers: 1+3= 4= 2 2 Sum of first 3 odd  numbers: 1+3+5= 9= 3 2 Sum of first 4 odd  numbers: 1+3+5+7=16= 4 2 Sum of first 5 odd  numbers: 1+3+5+7+9 = 25 = 5 2 Sum of first n odd  numbers: 1+3+5+7+9+. . . . .  n numbers= n 2 Now we will see average: Average of first 2 odd numbers= (1+3)/2                                                           = 4/2                                                                 =2 Average of first 3 odd  numbers= (1+3+5)/3                                                           = 9/3                                                                 =3 Average of first 4 odd  numbers= (1+3+5+7)/4                                                           = 16/4                                                                 =4 Average of first 5 odd numbers= (1+3+5+7+9)/5            
1 comment
Read more

LOGIC BEHIND MAGIC SQUARE

By
Assume a magic square of 3x3 A B C D E F G H I The above figure shows a 3x3 magic square. In the magic square sum of colum, row, diagnol numbers should be same A+B+C=D+E+F=G+H+I=A+D+G=B+E+H=C+F+I=A+E+I=C+E+G=sum A+B+C D+E+F G+H+I A+D+G B+E+H C+F+I A+E+I C+E+G By  seeing the  above there is 8 type of sum is available. Row wise-3,  column wise-3, diagnol wise-2. Condition#1: There are 8 different combinations are there with same sum in a magic square. In the above 8 combinations A=2 times, B= 3 times, C= 2 times, D=3 times E=4 times, F=3 times, G=2 times, H=3 times, I= 2 times Hence the above forms the condition#2. In simply condition#2, middle number E appears 4 times in 8 combinations. Hence row, column, diagnol sum should be equal. In 3x3 magic square we are taking numbers from 1 to 9. From 9 numbers we need to take 3 numbers. From combination f
1 comment
Read more

average of first n natural numbers

By
The natural numbers are 1,2,3,4,5,. . . . . . now we will see the sum of natural numbers                       sum of first 3 natural numbers= 1+2+3=6 the above can be written as                      sum of first 3 natural numbers= 1+2+3=6=3(3+1)/2                      sum of first 4 natural numbers= 1+2+3+4=4(4+1)/2                      then sum of n natural numbers=1+2+3+......n terms=n(n+1)/2 then the average formula = sum of elements/no of elements                     the average of n natural numbers= sum of elements/ no of elements                                                                         =(n(n+1)/2)/n                                                                         =n(n+1)/2xn                                                                         =(n+1)/2   THE AVERAGE OF FIRST N NATURAL  NUMBERS=(n+1)/2 The average of first 5 natural numbers                                  sum of 5 natural numbers=1+2+3+4+5=15            
Post a Comment
Read more