By David, 20 February 2019 Brainteaser

Which two whole numbers – without any zeros – multiply together to make 1 000 000?

Scroll down for the answer!

A good way to tackle this question is by breaking down 1 000 000 into smaller numbers.

1 000 000 = 10 x 10 x 10 x 10 x 10 x 10

And since 10 = 2 x 5, we know that:

1 000 000 = 2 x 5 x 2 x 5 x 2 x 5 x 2 x 5 x 2 x 5 x 2 x 5

We can reorder these:

1 000 000 = 2 x 2 x 2 x 2 x 2 x 2 x 5 x 5 x 5 x 5 x 5 x 5

And start grouping them again:

1 000 000 = 64 x 5 x 5 x 5 x 5 x 5 x 5

1 000 000 = 64 x 15625

Do you have another way of tackling the problem? Pop it in the comments below!

*For more brainteasers and puzzles for kids, subscribe to Double Helix magazine!*

Categories:

February 22, 2019 at 11:50 am

To answer the problem for 10:

2 X 5

Just keep doubling one side and halving the other to still make 10.

4 X 2.5

8 X 1.25

16 X .625

32 X .3125

64 X .15625

If we changed the magnitude of .15625, might we get the numbers we need? Let’s try.

64 X 15,625 = 1,000,000 Yes!

February 28, 2019 at 5:23 pm

Break it into 100s and then into 25 and 4