Question

Lucy wants to multiply 88 x 808. She says that all she has to do is find 8 x 808 and then double that number. Explain why Lucy's method will not give the correct answer. Then, show how to find the correct answer.

Answer 1

The multiplication that Lucy has to make is:

`88*808`

If she multiplies 8x808 and then multiplies the result by 2, she will not be finding 88x808, instead, she will be finding 16x808, (because 8x2 is 16):

`2(8*808)=16*808`

Thus, with that method, she will not get the correct result.

Let's find the correct method:

Going back to the original multiplication she has to make:

`88*808`

We can express the number 88 as 11x8:

`(11*8)*808`

And we represent this as follows:

`11(8*808)`

And we have found the correct method: she has to find 8x808 and then multiply the result by 11.

Answer: Find 8x808 and multiply the result by 11.