Working systematically

How many triples of points are there in this 4x4 array that lie on a straight line?

In how many different ways can a row of five "on/off" switches be set so that no two adjacent switches are in the "off" position?

Can you choose one number from each row and column in this grid to form the largest possibe product?

In Sam and Jill's garden there are two sorts of bugs with 7 spots or 4 spots. What numbers of total spots can you make?

On a digital clock showing 24-hour time, over a whole day, how many times does a 5 appear?

Can you work out the sum of the missing digits in this subtraction?

Two of the numbers in a 4x4 magic square have been swapped. Can you work out the sum of these numbers?

How many different phone numbers are there starting with a 3 and with at most two different digits?

If all the arrangements of the letters in the word ANGLE are written down in alphabetical order, what position does the word ANGLE occupy?

The digits 1-9 have been written in the squares so that each row and column sums to 13. What is the value of n?