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How do the digits in each product relate to the factor 9?
If they are multiples of 9, the digits add up to a multiple of 9.
What is the sum of the multiples of 9?
There are infinitely many multiples of 9 and it is not possible to add them all.
What is noticeable about the sum in the multiples of 9?
That the sum of its digits add up to 9 as for example 9*9 = 81 and 8+1 = 9
What is the first multiple of 9 that contains all even numbers?
288. All multiples of 9 will have digits that add to a multiple of 9. To get a multiple of 9 to be all even, you need to get them to add to 18, since no set of even numbers will add up to 9. 288 is the lowest multiple of 9 to be able to add to 18. ■
Is 498 a multiples for 9?
The digits of 498 do not add to a multiple of 9 so it isn't.
Can you think of another number pattern in multiples of 9?
The digital sum of multiples of 9 always add up to 9 as for example 9*9 = 81 and 8+1 = 9
How do the digits in each product relate to the factor 9?
If they are multiples of 9, the digits add up to a multiple of 9.
What is the sum of the multiples of 9?
There are infinitely many multiples of 9 and it is not possible to add them all.
What is noticeable about the sum in the multiples of 9?
That the sum of its digits add up to 9 as for example 9*9 = 81 and 8+1 = 9
What multiple of 9 is greater than 110 but less than 120?
117. All multiples of 9 have digits that add up to something divisible by 9. Examples, 117, 36, 45, 54 all have digits that add up to 9.
What is the first multiple of 9 that contains all even numbers?
288. All multiples of 9 will have digits that add to a multiple of 9. To get a multiple of 9 to be all even, you need to get them to add to 18, since no set of even numbers will add up to 9. 288 is the lowest multiple of 9 to be able to add to 18. ■
Is 498 a multiples for 9?
The digits of 498 do not add to a multiple of 9 so it isn't.
Why do no digits of a prime number add up to 9?
Because they're in multiples of three - a quick way to tell if a number is a multiple of three is to add up the digits and see if the digits add up to a multiple of three e.g 576, 5+7+6=18, 1+8=9, 9 is a multiple of three
List all multiples of 9 up to 750?
9
What are the multiples of 9 up to 300?
918273645546372819099108117126135144153162171180189198207216225234243252261270279288297306
What are multiples of 7 that add up to 112?
56 and 56
How can use use the digits 6 and 4 to decide if 64 is the product of 9 and 7?
So there is a rule about multiples of 9 in general: something is a multiple of 9 if and only if its digits add up to a multiple of 9. 6+4 = 10, so it is not a multiple of 9. There's also a neat trick to remembering the multiples of 9 below 99 with your fingers, but you can look this up if you're interested.
