In this activity, we will learn how to find the two consecutive numbers (neighbouring numbers) that multiply together to give a given number.

Example

Find the two consecutive numbers that multiply together to give the following number.

462 = _______ × _______

Answer

You need to think of clues.

1.     You should know that 20 x 20 = 400

2.     Look at the last digit, which is 2 here.  Think of consecutive numbers that multiply to give a final digit of 2.  They are 1 and 2 or 3 and 4 or 6 and 7 or 8 and 9.

3.     Now use trial and improvement.

462 =          21           ×          22