mathematics
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
&…
Examples 16 to 20 of Fundamental(Numbers)
(16) Find the unit’s digit in the product (5327)153 × (143)72.
Soln. First of all divide the index by 4 and find out its remainder.
( Replace the remainder 4 by 1 and oth…