Directions: Study the following questions carefully and choose the right answer:
1
7  of 58 +   3  of 139.2 = ? 
5 8

» Explain it
A
? =  7  of 58 +  3  of 139.2 = 81.2 + 52.2 = 133.4
5 8

Hence, option A is correct.

2
» Explain it
A
Method I :

? = 12% of 555 + 15% of 666

12  × 555 +  15  × 666
100 100

= 12 × 5.55 + 15 × 6.66

= 66.6 + 99.9 = 166.5

Method II :

? = 12% of 555 + 15% of 666

= (10 + 2)% of 555 + (10 + 5)% of 666

= 10% of 555 + 2% of 555 + 10% of 666 + 5% of 666

= 55.5 + 11.1 + 66.6 + 33.3   =   166.5

Hence, option A is correct.

3
84368 + 65466 – 72009 – 13964 = ?
» Explain it
C
? = 84368 + 65466 – 72009 – 13964

= 149834 – 85973 = 63861

Hence, option C is correct.

4
337.8 × 331.2 ÷ 335 = 33 × 33?
» Explain it
B
337.8 × 331.2 ÷ 335 = 33 × 33?

337.8 + 1.2 – 5 = 331 + ?

334 = 331 + ?

4 = 1 + ?

? = 4 – 1 = 3

Hence, option B is correct.

5
?  =  324
529 ?

» Explain it
D
?  =  324
529 ?

?2 = 529 × 324

? =  529 × 324  = 23 × 18 = 414

Note : We don't even need to multiply 23 into 18 to find the correct answer. We can observe the correct answer just by multiplying the unit digit of these two numbers, which will be 4.

Therefore, option 'D' can be immediately chosen.

Hence, option D is correct.