PINs are far more secure than their 4-digit counterparts - here's how and why to make the switch on both mobile and on PC.

There are lots of number patterns in Maths. There are odd numbers, even numbers, multiples, single-digit and two-digit numbers ... of tens first. 68 has 6 tens and 71 has 7 tens.

There are lots of number patterns in Maths. There are odd numbers, even numbers, multiples, single-digit and two-digit numbers ... of tens first. 68 has 6 tens and 71 has 7 tens.