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19 votes
19 votes
I NEED HELP!!
MY TEACHER Wouldnt EXPLAIN THIS TO ME PLZ HELP!!

I NEED HELP!! MY TEACHER Wouldnt EXPLAIN THIS TO ME PLZ HELP!!-example-1
User Amarjit Dhillon
by
2.5k points

1 Answer

9 votes
9 votes

Answer:

Your math teacher deserves to be fired.

The example for this is 1.23 × 4.5 (none of your questions, I know)

Anyway we want to do this lining up the digits like so:

1.23

× 4.5

NOT

1.23

× 4.5

Now we want to multiply all the digits (1, 2, 3) in the top number (1.23) by the 5 in 4.5. We'll start with the 3 in 1.23.

Since 3 × 5 is equal to 15, we will put the ones digit of 15, 5, in that place.

1.23

× 4.5

5

Now we need to carry the 1 in the 15 to be used in 2 (of 1.23) multiplied by the 5 (in 4.5). Now we will get 2 × 5 + 1 which equals 11. We carry the 1 in 11 to the next part.


_(1)

1.23

× 4.5

15

So we currently have the digits 15 for our answer. Now we move to the next part where we do 1 × 5 + 1 which is equal to 6. Our problem is now:


_(1)

1.23

× 4.5

615

Now we can move to the next row where we do the exact same thing where we multiply the digits in 1.23 BUT instead of 5, we now multiply them each by 4 since our number is 4.5. However this is different, before starting to multiply, we need to put a 0 in the ones digit of the 2nd row of our answer like so:


_(1)

1.23

× 4.5

615

+ 0

Now we can start to multiply.


_(1)

1.23

× 4.5

615

+ 20

then


_(1)

1.23

× 4.5

615

+ 920

then


_(1)

1.23

× 4.5

615

+4920

Now we are almost at our solution, we need to now add our 615 and 4920. That then is equal to 5535. Now since we have 3 digits in total in 1.23 & 4.5 BEHIND the decimal point, we need to put a decimal point 3 digits to the right of 5535 so then it becomes 5.535. Hopefully, this helps? I didn't answer them immediately because if you never learn how to do long multiplication (what this is called) then you'll likely fail at all other math. Trust me, I know, I've done that before, I hope you don't make the same mistake because the feeling when everyone else is ahead of you and you're still at the basics is horrible.

Anyway answers for your question because I think I'll likely be reported for not answering your question:

40.725 | 9.576 | 17.442 | 45.29

79.294 | 30.736 | 30.8 | 31.5

25.85 | 53.29 | 49.184 | 15.18

User Jaynp
by
3.1k points