17 x 10= 7 x 7 and 7 x 10 What law in mathematics

[puzzleking123]

When I work out 17 x 10 I do 7 x 7 and 7 x 10 then add the answers together, what law am I using, explain your answer

[bibblebub]

when multiplying by 10 just ad an 0 to the end

where do you get 7x7 from?

[factor-fiction]

The law of nonsense mathematics.
17 x 10 =170
7 x 7 =49 and 7 x 10 = 70, and the total is 49+70 = 119

[factor-fiction]

Maybe you need someone to proofread your questions.
Did you mean 17 x 10 = (10 x 10) + (7 x10)?

[Buenchico]

. . . and if you did mean what Factor30 suggested, you're using the axiom that multiplication is distributive over addition.

[Prudie]

Do you read your questions - this is nonsense
What law? Coles law

[bibblebub]

i reckon that it's supposed to be 17x7 = 10x7 + 7x7

[sophie_1003]

If you'd said 17x10=
10x10=100
7x10=70
100+70=170
I would have said you were using partitioning and possibly associative/commutative? property but seeing as you have done 7x7 I don't know what you're reasoning would be!

[factor-fiction]

Hi bibblebub- yes when we were at school we were taught to add a zero when multiplying whole numbers by 10 and move decimal points when multiplying/dividing by powers of 10.
But that approach is very much frowned upon now in case pupils think 2.4 x 10 = 2.40- pupils have to be told to move all the digits to the left or to the right.

[sophie_1003]

distributive! That's the one I was looking for Buenchico!

[factor-fiction]

Did these answers help?

[New Judge]

Very helpful, thanks.

I now know that 17 x 10 is 170 and not, as I thought, 119 !!

[mike11111]

Good on multiplication, methyl but more work needed on the addition.

[factor-fiction]

I wonder if puzzleking123 will come back to clarify the question.

[squarebear]

It is long multiplaication. However, your question is nonsense as others have said.