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What's the units digit Questions?

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What's the units digit Questions? [#permalink] New post 31 Mar 2008, 17:09
I can't count the number of questions I've come across of this nature:

What is the units digit of (9^3)(4^5)(6^3)?

any ideas as to how I can solve questions like this?
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Re: What's the units digit Questions? [#permalink] New post 31 Mar 2008, 17:15
(9^3)(4^5)(6^3) can be re-written as
=(9*4*6)^3 * 4^2
= (216)^3 * 16

As 6^3 = 216 (6 cube ends in 6, so 216 cube will also end in 6)

xxxxxxxx6 * 16

Will end in 6.
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Re: What's the units digit Questions? [#permalink] New post 31 Mar 2008, 17:19
1) 9*9*9 = 729
2) 44444 = 1024
3) 666 = 216

basically you take the units digit from each of numbers which is...9,4,6 then multiply those numbers
9*4*6 = 216

Answer is 6.
Anyone know a faster way?
Re: What's the units digit Questions?   [#permalink] 31 Mar 2008, 17:19
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