Question

how many three digit number are there divisible by 3 find their sum​

Answer 1

Answer:-

102,105,108,............................999.

From above AP,

we have,

a= 102

d= 3

an= 999

n=?

Sn= ?

By Formula ;- an= a+ (n-1) d

999= 102 + (n-1) 3

999-102= (n-1)3

897= (n-1)3

897/3 = n-1

299+1= n

n= 300

By Formula ;- Sn= n/2 (a+l)

Sn= 300/2 (102+999)

150*1101

Sn= 165,150

Hope it will help u:)

Answer 2

According to given condition;

Three digits Number Divisible By 3

102,.........999

Given:

(First term)=a=102

(Common Difference)=d=3

(last term)=tn=999

Solutⁿ:. tn=a+(n-1)d

999=102+(n-1)3

999=102+3n-3

999+3=102+3n

1002=102+3n

900=3n

n=300

300 three digits Number Divisible By 3

According to Second Condition;

Sn=n/2 [t¹+tⁿ]

=300/2 [102+999]

= 150 [1101]

= 1251

The Sum of three digits Number Divisible By 3 is 1251.