A warehouse has all item serial numbers from 1 to 120. The manager wants to identify items whose serial number contains the digit 5, but are not divisible by 5 (for labelling purposes). How many such item serial numbers are there?
(a) 10
(b) 8
(c) 15
(d) 17

Question

A warehouse has all item serial numbers from 1 to 120. The manager wants to identify items whose serial number contains the digit 5, but are not divisible by 5 (for labelling purposes). How many such item serial numbers are there?
(a) 10
(b) 8
(c) 15
(d) 17

ONLiNE UPSC · Accepted Answer

Among the numbers from 1 to 120, those containing the digit 5 include: 5, 15, 25, 35, 45, all numbers from 50 to 59 (10 numbers), and others like 65, 75, 85, 95, 105, and 115, totalling 21 numbers. Of these, the ones divisible by 5 are 5, 15, 25, 35, 45, 50, 55, 65, 75, 85, 95, 105, and 115 &mdash; 13 numbers in total. Therefore, the numbers that contain the digit 5 but are not divisible by 5 are 21 &minus; 13 = 8.
Hence, option b is correct.

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M Question 1	⏱ 0
A warehouse has all item serial numbers from 1 to 120. The manager wants to identify items whose serial number contains the digit 5, but are not divisible by 5 (for labelling purposes). How many such item serial numbers are there? (a) 10 (b) 8 (c) 15 (d) 17