GMAT PREP 1 Question what is the remainder

Sure,

question: 3^(4n+2)+m/10=? remainder
4n+2= 6,10,14,18 always 4 apart so 3^(4n+2)/10= always remainder 9.

1. n=2

Nothing new we know already that for every n the unit's digit is 9. We know nothing about m so //insuff

2. m=1

3^(4n+2)+1= 0 unit's digit so remainder = 0 //suff

Hence, B

Don't have much time atm so if you still have any questions replay. I will do my best to answer it in more detail after a dinner.

It should be B)


Stmt I

n=2

3^4(2)+2 = 3^10 will have units digit 9

If m=1 then the 9+1 the units digit of the resulting number will be 0 and therefore divisible by 10
If m=2 then the remiander will be 1

Any remiander value from 0 to 9 possible depending on the value of m
INSUFF


Stmt II

m=1

3^(4n+2) will have unbits digit of 9 always for n=1,2,3.... so really we dont need the balue of n. All we need is one defniite value for m which is given to be 1

If m=1 then the 9+1 the units digit of the resulting number will be 0 and therefore divisible by 10

SUFF


Choose B)

Units digit iof 3 cycle as follows

3,9,7,1,3,9,7,1,3,9,7,1..... so on

Many Thanks Cramya and zipper

cramya wrote:Units digit iof 3 cycle as follows

3,9,7,1,3,9,7,1,3,9,7,1..... so on

if the pattern is different, how is the unit digit is when divided by 10?

I'm confused.

if the pattern is different, how is the unit digit is when divided by 10?

I'm confused.

The pattern is the same it repeats as follows

3,9,7,1,3,9,7,1,3,9,7,1,3,9,7,1,

if n=1 4n+2 is 6
if n=2 4n+2 is 10

As u can see for n=3,4... 4n+2 value changes but the units digit always is 9

We really dont need n(givenj as positive integer cant be 0 so we start with 1) as we can substitute1,2,3 etc... Hence we need just m to get to one defnite answer

Hope this helps! Let me know if u still hv questions.