Que: Find the number of trailing zeroes after the rightmost non-zero digit in the value of 55!?
A) 3
B) 5
C) 7
D) 11
E) 13
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Que: Find the number of trailing zeroes after the rightmost non-zero digit in the value of 55!?
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Max@Math Revolution
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Max@Math Revolution
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Solution: 55! = 55 * 54 * 53 *………. * 3 * 2 * 1
=> When ‘5’ is multiplied by an even number, it results in ‘0’.
=> Numbers in 55! , which has ‘5’ as the factor are: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55
=> 25 and 50 will have ‘2’ (5’s). Hence, we have 13 ‘5’s’ and at least 13 even numbers in 55! , which when multiplied by 5 will result in ‘0’.
E is the correct answer.
Answer E.
=> When ‘5’ is multiplied by an even number, it results in ‘0’.
=> Numbers in 55! , which has ‘5’ as the factor are: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55
=> 25 and 50 will have ‘2’ (5’s). Hence, we have 13 ‘5’s’ and at least 13 even numbers in 55! , which when multiplied by 5 will result in ‘0’.
E is the correct answer.
Answer E.
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