Question

18- What will be the unit digit of
243 ?
a. 8
b. 6
c. 2
d. 4​

Answer 1

Answer:

3^5=243 (the units digit is 3 again!)

Answer 2

Answer:

c)-2

Step-by-step explanation:

For the concept of identifying the unit digit, we have to first familiarize with the concept of cyclicity. Cyclicity of any number is about the last digit and how they appear in a certain defined manner. Let’s take an example to clear this thing:

The cyclicity chart of 2 is:

21 =2

22 =4

23 =8

24=16

25=32

Have a close look at the above. You would see that as 2 is multiplied every-time with its own self, the last digit changes. On the 4th multiplication, 25 has the same unit digit as 21. This shows us the cyclicity of 2 is 4, that is after every fourth multiplication, the unit digit will be two.

Hope this helps u