Question

The Digit in the unit place of the product 127^79 * 2^24?

Answer 1

@UnkleRhaukus

Answer 2

plzz help

Answer 3

can i use a calculator?

Answer 4

no

Answer 5

any tricks???

Answer 6

calculator didn't help at all

Answer 7

i think there is some tricks to do it....

Answer 8

can you make 127 simpler?

Answer 9

i can not see the trick to this yet

Answer 10

@heena plzz help

Answer 11

well it turns out that 127 is a prime number

Answer 12

i dont know if this helps or not

Answer 13

@heena can u solve this......

Answer 14

wait lemme see i didnt read qn yet lol :P

Answer 15

ok

Answer 16

it so long :O @Ishaan94 u have scientific calculator plz do dis..

Answer 17

i think there is a trick for doing this

Answer 18

the product has over 170 places,
a calculator will not help here

Answer 19

7^1 = 7
7^2 = 49
7^3 = ...3
7^4 = ...1
7^5 = ...7

2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32


127^79 = ...1?
2^24= ...6?

So, 6?

Answer 20

The answer is 8 plzz check it

Answer 21

Ohh hmm I must have done silly mistake

Answer 22

Yes, 127^79= ...3
6x3 = 18 and 8 is the answer

Answer 23

can u tell the tricks used..

Answer 24

i do not understand how you did that @Ishaan94

Answer 25

Hmm 23*24 = ...2, we only need to get multiplication of the digits in unit place. so, to get unit place digit for 127^(79)*2^(24), we need get unit place of 7^(79)*2^24

Answer 26

yeah i get that bit , but i don not get how you found the unit place of 7^{79}=....3

Answer 27

how u get the unit digit for 2^24 as 6 and other as 3//

Answer 28

@satellite73

Answer 29

their unit digits repeat after certain number of multiplication.

7^1 = 7
7^2 = 49
7^3 = 343
7^4 = 2401
7^5 = 16807
7^6 = 117649
7^7 = 823453
7^8 = 5 764 801

try to see the pattern you will realize.
i am not a good teacher, sorry.

Answer 30

so.....

Answer 31

i think i see what you are getting at @Ishaan94

Answer 32

after 4 powers, 7 gets back to 1st form. 79 = 80 -1 => 79=4*20 - 1. so, 7^79 must be of ...3 form

Answer 33

i didn't know there were such patterns for powers

Answer 34

then for 2^24

Answer 35

Try it yourself. :-)

4,8,16,32,...

Answer 36

so it repeates after 6 so 2^24 must be 6 is that the way

Answer 37

No not 6 but 4

2,4,8,16,32,64,128,256,512,...

Answer 38

hey it repeates after 16

Answer 39

it does, but the actual interval is 4 not 16.

Answer 40

ok

Answer 41

1,3,9,27,81,243,279,2197,..1,..3,..9,..7,..1,..3,...9,...7,......

Answer 42

kinda reminds me of repeating decimals

Answer 43

I got it)))
http://www.wolframalpha.com/input/?i=127%5E79+*++2%5E24
The last digit in the resultant number is 8.