www.youtube.com/watch?v=0VG1...
www.youtube.com/watch?v=0VG1...
reversedNumber = 0 * 10 + 1 = 1
reversedNumber = 1 * 10 + 2 = 12
reversedNumber = 12 * 10 + 1 = 121
reversedNumber = 0 * 10 + 1 = 1
reversedNumber = 1 * 10 + 2 = 12
reversedNumber = 12 * 10 + 1 = 121