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

A father is 5 times as old as his son. His son is 6 years old. His son is 6 years old. After how many years, will the father be 4 times as old as his son?

Which two signs need to be interchanged to make the following equation correct?
45 – 9 ÷ 3 +5 ×6 =32

If ‘+’ denotes ‘ –‘  and ‘ – ‘ denotes ‘×’  and ‘×’  denotes ‘÷’ and ‘÷’ denotes ‘+’ then what will be the numeric value of 60 × 10 ÷ 40 + 6 – 5 

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?