find the sum of integers between 100 and 200 that are divisible by 3 and 7.
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Numbers which are divisible by 3 are 102,105,108......................198
Total numbers 198=102+(x-1)3
198-102=(x-1)3
96=(x-1)3
x-1=32
x=33
Sum of these numbers
=33/2[2(102)+(33-1)3]
=33/2[204+96]
=33/2(300)
4940
Numbers which are divisible by 7 are 105,112,119.......................196
Total numbers 196=105+(x-1)7
x=14
Sum of these numbers
=14/2[2(105)+(14-1)7
=2107
Numbers which are divisible by 21 are 105,126,147....................189
Sum of these numbers=735
Sum of integers which are divisible by 3 and 7= 4940+2107-735
ANSWER=6312
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