Challenge Level

48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?

Challenge Level

Find at least one way to put in some operation signs (+ - x Ã·) to make these digits come to 100.

Challenge Level

Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.

Challenge Level

Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?