What is the unit digit in
$$\begin{aligned} (6324)^{1797} \times (615)^{316} \times (341)^{476} \end{aligned}$$

Answer: Option D

Answer: Option B

Explanation:

(555 + 445) * 2 * 110 + 30 = 220000 + 30 = 220030

Answer: Option C

Explanation:

$$\begin{aligned} \frac {1}{2}\times 2(a^2 + b^2) = \frac {1}{2} \times [(a + b)^2 + (a - b)^2] \end{aligned}$$
$$\begin{aligned} = \frac {1}{2} \times [(217 + 183)^2 + (217 - 183)^2] = 80578 \end{aligned}$$

Answer: Option B

Explanation:

Trick: when multiplying with $$\begin{aligned} 5^n \end{aligned}$$ then put n zeros to the right of multiplicand and divide the number with $$\begin{aligned} 2^n \end{aligned}$$
So using this we can solve this question in much less
time.
$$\begin{aligned} 1939392 \times 5^4 = \frac {19393920000}{16} = 1212120000 \end{aligned}$$

Answer: Option A