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rohit.reddy
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in 214 ^ n (214 * 214 * 214 * 214 ....)
the last digit is in pattern 6,4,6,4... similarly in 149 its 1,9,1,9...
6+9 in units place will leave 5
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then $127/mo
units place is...
Source: Beat The GMAT — Problem Solving |
Hi Satish:satish.nagdev wrote:in 214 ^ n (214 * 214 * 214 * 214 ....)
the last digit is in pattern 6,4,6,4... similarly in 149 its 1,9,1,9...
6+9 in units place will leave 5
How did u get 6 for 214^870 and not 4?
I got 9 in 149^127 because of 9x9x9x9x9x9x9 = 7th 9-digit because its power ends in 7 (127).
Could you help me please?
Thank you,
Silvia
For every odd power (214^1, 214^3, 214^5 etc) the unit's digit is 4 (214^1=214,214^3=9,800,34). For every even power (214^2, 214^4 etc) the unit's digit is 6. So for 214^870, the unit's digit is 6.ssuarezo wrote:Hi Satish:satish.nagdev wrote:in 214 ^ n (214 * 214 * 214 * 214 ....)
the last digit is in pattern 6,4,6,4... similarly in 149 its 1,9,1,9...
6+9 in units place will leave 5
How did u get 6 for 214^870 and not 4?
I got 9 in 149^127 because of 9x9x9x9x9x9x9 = 7th 9-digit because its power ends in 7 (127).
Could you help me please?
Thank you,
Silvia
Work the same way with 149: for 149^1, the unit's digit is 9, for 149^2, the digit is 1. Since 127 is odd, the unit's digit of 149^127 is 9.
9+6=15.
I hope that helps
thank you djkvakin (don't know how to read it ! )djkvakin wrote: For every odd power (214^1, 214^3, 214^5 etc) the unit's digit is 4 (214^1=214,214^3=9,800,34). For every even power (214^2, 214^4 etc) the unit's digit is 6. So for 214^870, the unit's digit is 6.
Work the same way with 149: for 149^1, the unit's digit is 9, for 149^2, the digit is 1. Since 127 is odd, the unit's digit of 149^127 is 9.
9+6=15.
I hope that helps
Find the units digit of 214^870 + 149^127.
1. 7
2. 1
3. 3
4. 9
5. 5
The simplest way of solving such questions as per me is
divide the powers by 4 and see the remainders:
i.e.
870/4 gives the remainder 2 and then raise 214 by 2 and then the unites digit is 6.
now divide 127/4 and the remainder is 3 and then raise 149 by 3 and the units digit is 9
So 6 + 9 = 15 so units digit is 5.
Cheers
1. 7
2. 1
3. 3
4. 9
5. 5
The simplest way of solving such questions as per me is
divide the powers by 4 and see the remainders:
i.e.
870/4 gives the remainder 2 and then raise 214 by 2 and then the unites digit is 6.
now divide 127/4 and the remainder is 3 and then raise 149 by 3 and the units digit is 9
So 6 + 9 = 15 so units digit is 5.
Cheers
