Question

find the sum of all natural numbers less than 200 and divisible by 5
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Answer 1

Answer:

Step-by-step explanation:

we will use the sum of natural number series formula

if S=1+2+3+4+........+n, then

S= n(n+1) ;

2

Now, sum of all +ve integers from 0 to 200 is given by

S=0+1+2+3+.......+200

=> S=200(200+1)/2;

=>S=20100;

Sum of all +ve integers divisible by 5 is given by

R=0+5+10+15+20+25+30+.........+200

R=5(1+2+3+4+5+6+.........+40)

R=5*40(40+1)/2

R=4100 ;

therefore the sum of all +ve integers <200 and not divisible by 5=S-R=16000