Number of 4-digit numbers that are less than or equal to 2800 and either divisible by 3 or by 11 , is
equal to
710
210
320
415
4 digit number which are less then 2800 are 1000 – 2799
Number which are divisible by 3
2799 = 1002 + (n – 1) 3
n = 600
Number which are divisible by 11 in 1000 – 2799
= (Number which are divisible by 11 in 1 – 2799)
– (Number which are divisible by 11 in 1 – 999)
Number which are divisible by 33 in 1000 – 2799
= (Number which are divisible by 33 in 1 – 2799) – (Number which are divisible by 33 in 1 – 999)
total number = n(3) + n(11) – n(33)
= 600 + 164 – 54 = 710
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