What is the remainder when 2^20 is divided by 10

Hi lheiannie07,

We're asked for the remainder when 2^20 is divided by 10.

To start, the GMAT would never expect you to calculate a number as big as 2^20, so there must be a pattern behind 'powers of 2' (and there is). The units digit of the powers of 2 follows a consistent pattern:

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

2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256

Notice that the units digits follow the pattern: 2, 4, 8, 6.... 2, 4, 8, 6

The 20th power would be 5 groups of 4 values - and it would be the 4th value of that last group. Thus, it will equal 6.

Final Answer: D

GMAT assassins aren't born, they're made,
Rich