Some equations are solved on the basis of a certain system. Find out the correct answer for the unsolved equation on that basis.
If 8 + 8 = 72, 5+5 = 30 and 7+7=56, what is 6+6 =?

Select the set in which the number are related in the same way as are the number of the following set.
( 11, 16, 20)

How many numbers are there between 1 and 100 which start or end at 2? 

If "÷" denotes "multiplied by", "+" denotes "subtracted from", "x" denotes "added to" and "–" denotes "divided by",then
12 – 6 + 28 × 3 ÷ 9 = ?

If 2 is added to each even digit and 1 is subtracted from each odd digit in the number 621754, then what will be the sum of number/numbers not repeated in the new number?

If two is subtracted from each odd digit and three is added to each even digit in the number 3675249 how many digits will appear twice in the new number thus formed?