Question

Find the number of natural numbers between 102 and 998 which are divisible by 2 and 5 both.

Answer 1

As the numbers are divisible by both 2 and 5,so their last digit will always be 0. hence the series are 110,120,130,....,990

here a=110,d=10,an=990

an=a+(n-1)d

990=110+(n-1)10

(n-1)10=880

n-1=88

n=88+1

n=89.

thus the number of natural numbers between 102 and 998 which are divisible by both 2 and 5 is 89.

Answer 2

Answer:

Step-by-step explanation:First , the no. Between 102 & 998 which is divisible by 2 &5 is 110 , 120,130 and so on up to 990. So it forms an AP . a= 110 , d= 10 , l = 990. By using formula- l= a+ (n-1)d

990= 110 + (n-1)10

990-110 = (n-1)10

880/10 = n-1

88 = n-1

89 = n