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# What is the units digit of the product of any five consecutive positiv

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 8025
GMAT 1: 760 Q51 V42
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What is the units digit of the product of any five consecutive positiv  [#permalink]

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08 Mar 2019, 02:39
1
00:00

Difficulty:

5% (low)

Question Stats:

94% (00:37) correct 6% (00:46) wrong based on 49 sessions

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[GMAT math practice question]

What is the units digit of the product of any five consecutive positive integers?

A. 0
B. 2
C. 4
D. 6
E. 8

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MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
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"Only $79 for 1 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" e-GMAT Representative Joined: 04 Jan 2015 Posts: 3078 Re: What is the units digit of the product of any five consecutive positiv [#permalink] ### Show Tags 08 Mar 2019, 02:49 Solution To find: • The units digit of the product of any five consecutive positive integers Approach and Working: If we consider any five consecutive positive integers, then among those five integers • 1 multiple of 5 will be always present • At least 2 multiples of 2 will be always present. Now, if we multiply a multiple of 5 with an even number (multiple of 2), then the product will be always a multiple of 10. • Therefore, the units digit of the product = 0 Hence, the correct answer is option A. Answer: A _________________ Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 8025 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: What is the units digit of the product of any five consecutive positiv [#permalink] ### Show Tags 10 Mar 2019, 18:22 => Since one of the five consecutive integers must be a multiple of $$5$$ and one must an even number, their product is a multiple of $$10$$. Thus, the units digits of the product is $$0$$. Therefore, the answer is A. Answer: A _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$79 for 1 month Online Course"
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Re: What is the units digit of the product of any five consecutive positiv  [#permalink]

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11 Mar 2019, 08:12
MathRevolution wrote:
[GMAT math practice question]

What is the units digit of the product of any five consecutive positive integers?

A. 0
B. 2
C. 4
D. 6
E. 8

Since we know that the product of 5 consecutive integers will always have prime factors of 2 and 5, the units digit of that product will always end in a zero.

Alternate solution:

Since the product of any five consecutive positive integers is divisible by 5! = 120, then the units digit of the product must be 0.

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Re: What is the units digit of the product of any five consecutive positiv   [#permalink] 11 Mar 2019, 08:12
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