Explanation

Two hundred one million = 201,000,000  

Five hundred six thousand = 506,000  

Twelve = 12  

Sum = 201,000,000 + 506,000 + 12 = 201,506,012  

Explanation

25% of Rs. 1600 = 0.25 × 1600 = Rs. 400  

5% of Rs. 400 = 0.05 × 400 = Rs. 20  

Explanation

3x - 15 - 6 = 0 → 3x - 21 = 0 → 3x = 21 → x = 7  

Explanation

15% of 40 = 0.15 × 40 = 6  

Let the number be x.  

6 = 0.25x + 2 → 6 - 2 = 0.25x → 4 = 0.25x → x = 16  

Explanation

Let the number be x.  

200% of x = 140 → 2x = 140 → x = 70  

160% of x = 1.6 × 70 = 112  

Explanation

Total books = 65 + 50 = 115  

Total cost = 1150 + 920 = Rs. 2070  

Average price per book = 2070 ÷ 115 = Rs. 18  

Explanation

Order the numbers: 9.9 > 0.99 > 0.9 > 0.099  

Correct order: 9.9, 0.99, 0.9, 0.099

Explanation

Look at the hundredths place (6). Since it is 5 or more, round the tenths place (8) up by 1 → 3.9

Explanation

Two hundred one million = 201,000,000  

Five hundred six thousand = 506,000  

Twelve = 12  

Sum = 201,506,012

Explanation

20 is divisible by 1 (every number is) and also by 2, 4, 5, 10, but from the options, only 1 fits.  

3 and 7 do not divide 20 evenly.