Oh, I get it finally! Wow, I didn't think I had to think like that lol! :D
Ok, I'll skip no. 20 for later, that was pretty a 'logical' question.
21.
A palindromic number is a 'symmetrical' number which reads the same forwards and backwards. For example, 55, 101 and 8668 are palindromic numbers. There are 90 four-digit palindromic numbers. How many of these four-digit palindromic numbers are divisible by 7?
a. 7
b. 9
c. 14
d. 18
e. 21
How am I supposed to find that in about 2 minutes? :confused: I would like to know the 'trick'