7589 - X = 3434

Answer: Option D

Answer: Option C

Explanation:

(1056 / 23) gives remainder 21

21 + 2 = 23, So we need to add 2

Answer: Option A

Explanation:

On dividing 427398 by 15 we get the remainder 3, so 3 should be subtracted

Answer: Option A

Explanation:

Trick: Number is divisible by 9, if sum of all digits is divisible by 9, so (2+2+3+*+4+3+1) = 15+* should be divisible by 9,
15+3 will be divisible by 9,
so that least number is 3.

Answer: Option C

Explanation:

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