Question

Show that 7n cannot end with digit 0

Answer 1

I we factorise 7 we have 7×1
So there is not 2 or 5 in the factor so it cannot be end with 0

Answer 2

Answer:

7ⁿ can not end with 0

Step-by-step explanation:

n = 0     7⁰ = 1

n=1        7¹ = 7

n = 2     7² = 49

n = 3     7³ = 343

n = 4     7⁴ = 2401

7⁴ ends with 1    

number ending with 1 multiplied by any number  ends with the number multiplied ending with

n = 4a , 4a +1  , 4a + 2 , 4a + 3  

7ⁿ end with 7⁴ᵃ   or 7¹*7⁴ᵃ  or 7²*7⁴ᵃ  or 7³*7⁴ᵃ

7⁴ᵃ end with 1  

7¹*7⁴ᵃ end with 7  

7²*7⁴ᵃ end with 9  

7³*7⁴ᵃ end with 3  

=> 7ⁿ can end with 1 , 3 , 7 or 9

=>  7ⁿ can not end with 0