Multiples of 9 (For Kids) Trivia Quiz

Answer:

Hopefully that wasn't too hard!

Multiples of 9 are just the numbers you get when you keep adding 9 over and over. That's all multiplication is. It's like our friend 9 is taking steps along the number line, and each step lands on a new number: 9, 18, 27, 36, 45, etc.

Some steps are small, like 9 × 2 = 18. Those are the early stops on the number line. If you keep going, the numbers get bigger: 9 × 12 = 108. Every one of those comes from multiplying 9 by something. The number we get from multiplying two other numbers is called a product.

Here are all the multiples of 9 from the quiz:

18 = 9 × 2
27 = 9 × 3
36 = 9 × 4
72 = 9 × 8
90 = 9 × 10
99 = 9 × 11
108 = 9 × 12
180 = 9 × 20
450 = 9 × 50
999 = 9 × 111

The other numbers (37, 11, 83, 181, and 751) don't come from multiplying 9 by any whole number, so they're not multiples of 9. In fact, they're called prime numbers, because you can only get those products by multiplying the number itself by 1.

There's a really cool trick for figuring out if a number is a multiple of 9: if the digits of a number add up to 9 or some other multiple of 9, then the number itself is a multiple of 9!

Here are some examples:

Is 18 a multiple? Let's look. 1 + 8 = 9, so yes! What about 108? 1 + 0 + 8 = 9. It's also a multiple of 9. 27? 2 + 7 = 9. Works like a charm!

A little trickier one is 999. If we add 9 + 9 + 9, we get the sum of 27. We already learned above that 27 is a multiple of 9 (9 × 3), so again, we know that it's a multiple of 9.

If you try 37 (3 + 7 = 10) or 751 (7 + 5 + 1 = 13), it doesn't work. They're not multiples of 9.