Solution:
Formula for finding the sum of odd numbers:n^2
As we know n is nmbr of values
So UpTo 50 there must be 25 odd numbers .
n=25 if there is any kind of doubt so let me explain the odd numbers..
1,3,5,7,9,11,13,15,17,19,21,23,27,29,31,33,35,37,39,41,43,45,47,49
Now you can count these numbers.
So, I'm going to put the values in above formula.
n^2
25^2
625

Solution:
Formula : n(n+1)
Here n is equal to number of digits.
So we can find even nmbr UpTo 100 by dividing it with 2
100/2 =50
So, n=50
By putting the values in above formula
n(n+1)
50(50+1)
50(51)
2250

Solution:
250 X 4%
=250 X 4/100
=250 X 1/25
=250/25
=10Answer

Solution:
Loss=Cost price- selling price
=RS.4000-Rs.2500
=RS.1500
Loss percentage=(loss/cost price)X100
=(1500/4000)X100
Loss percentage=37.5%