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How many numbers between 1 and 100 (inclusive) are divisible by 7 or 10?

 Mar 2, 2018
 #1
avatar+37155 
0

100/7 = 14 .28 ~ 14 numbers

100/10 =10 numbers

24 numbers total are divisible by 10 or 7

 

One number ( 70 ) is divisible by 10 AND 7

 Mar 2, 2018
 #2
avatar+129907 
+1

N (divisible  by 7 or 10)   = N(divisible by 7)  + N (divisible by 10)   -  N (divisible by 7 and 10)  =

 

(14)   +  (10)  -   1   =

 

23

 

 

 

cool cool cool

 Mar 2, 2018
 #3
avatar+37155 
0

Ack ! TRUE !    I counted 70 twice...bummer !

ElectricPavlov  Mar 2, 2018

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