Examples 26 to 30 of Fundamental(Numbers)
(26) Find the sum of all odd numbers up to 100.
Soln. The given numbers are 1, 3, 5, 7, …, 99.
∴ = 2n – 1 ⇒ 2n – 1 = 99
∴ n = 50
…
Examples 21 to 25 of Fundamental(Numbers)
(21) What least number must be added and subtract to 3000 to obtain a number exactly divisible by 19 ?
Soln. On dividing 3000 by 19, we get 17 as a remainder.
∴ Number to be added
= ( 19 – 17 )
= 2
&…