Look at this series: F2, __, D8, C16, B32, ... What number should fill the blank?
A). E4
B). F5
C). G8
D). H4
E4
The letters decrease by 1; the numbers are multiplied by 2.
1. 7.8% of 12.5 + 2.5% of 161 = ?
2. The sum of two numbers is 231 and their HCF is 21. How many pairs of such numbers are there?
3. Look at this series: VI, 10, V, 11, __, 12, III, ... What number should fill the blank?
4. Look at this series: 1000, 200, 40, ... What number should come next?
7. Sum of the digits number is 8 and their product is 12. Find the difference between the digits?