can anyone solve these questions?plz help

[anushey]

1)the question is that was is the unit value of 7^1600 i.e (seven rasied to power 1600).i put this value in calculator but it gave maths error.does anyone knows how to solve this tricky question.
2)Also can anyone tell me for how many intergers is this true that:
X-1 >=0 and X+1<=0
the choices were A zero
B one
c-two
d)more than two.????

 

[PhyZac]

1) Is such a huge number for a calculator to solve ! - PLus - i dont know how to solve manually.

2) I think it is D ... Because.... in X - 1 >=0 ...lets consider X is 1..1-1 = 0 ...consider x =2 2-1=1 and so on..All positive values will work....and in x+1 <=0 ....consider x= -1 ...-1+1 = 0...and so on...with ALL negative number.....

 

[anushey]

1) Is such a huge number for a calculator to solve ! - PLus - i dont know how to solve manually.

2) I think it is D ... Because.... in X - 1 >=0 ...lets consider X is 1..1-1 = 0 ...consider x =2 2-1=1 and so on..All positive values will work....and in x+1 <=0 ....consider x= -1 ...-1+1 = 0...and so on...with ALL negative number.....

Thanks but for qs 2 a number should satisfy both the equations not just one.

 

[mercedes008]

peace, i found this, dont ask me how did i do it cause i did not,
Reduce 7^1600 mod 10: 7^1600 (mod 10) = (49)^800 (mod 10) = (-1)^800 (mod 10) = 1 (mod 10) So ones digit is 1 AND one more answer 1435040053331780864914254863669045794602…
03233816887322072785675577672231623553…
43826738006328775246738232799201792481…
91605397046249002131508935077932533397…
85061999921733434751183681938928340705…
36425531989083598351172580143983534723…
39761254364852320060637107738707040343…
62890075819908411459648483874859542360…
50932050130609990422778843520869164614…
64879416736008750190574949879271129679…
35279036602140783722445782588620682037…
48610824940827671002823185667663528292…
42427397496697903004551977467458192077…
38246504339175278687535679062611043645…
79718026119262575514465311477824897119…
37074341228361454487756500095532684132…
23291611175143257592044010248482107848…
53631924566042785062262560801715041273…
47981005688367011924334002395089740116…
24274162157822848960001 I can not validate any of the above though
peace