**Last Digit / Units Digit **

**To find the units digit of x ^{y} we only consider the units digits of the number x.
**

**To calculate units digit of 237**

^{234}we only consider the units digit of 237. Hence, we find the units digit of 7^{234}.**To find the units digit of a × b, we only consider the units digits of the numbers a and b.**

**To calculate units digit of 233 × 254, we only consider the units digit of 233 and 254 i.e. 3 and 4, respectively. Hence, the units digit of 233 × 254 = units digit of 3 × 4 i.e 2.**

**Problems for practice**

**1. Find the unit digit of [ 10 ^{20000} / ( 10^{100} +3) ] where [ x ] is greatest Integer less than or equal to x.**

**2. Find the unit digit of the product of first 120 primes .**

**3. What is the unit digit of 1! + 2! + 3! + 4! +….. + 2018! ?**

**4. What is the unit digit of (1! + 2! + 3! + 4! +….. + 2018!)**

^{2}?**5. What is the unit digit of 23**

^{1001}?**Some more ‘Gyan’ on numbers :**

Nifty Formulae for Natural Numbers

Divisibility Rule of a Number (Divisibility Test)

Remainders theorem

Divisors of a Number ( Number of Divisors of a number)

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