Question

find the sum of all multiples of 2 or 3 between 100 and 200 (100 and 200 are not included)

Answer 1

sum of common multiples of 2 and 3 ,
total numbers divisible by 2 and 3 =17.
a=102
l= 198
sn= n/2 (a + l)
sn = 17/2 (102 + 198 )
sn = 17/2(300)
sn = 17 * 150
sn (of common multiples of 2 and 3) = 2550

if you want both separately,
only multiples of 2, 
number of multiples = 50-1 (excluding 100)
a =102
d =2
n =49
an =198
sn = n/2 ( a+l)
sn =49/2 (300)
sn = 49 * 150
sn( of 2)=7350

only multiples of 3,
total numbers =33
a=102
d=3
n =33
an = 198
sn = n/2 (a+l)
sn= 33/2(300)
sn ( of 3) = 4950

hope it helps!!!!!

Answer 2

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