The trick I am going to explain is called the cross-multiplication technique... but not the one you know.
Let’s start with 123 * 456. Echague Isabela
Step 1--- arrange the numbers in order (one on top of the other) your pick.
123
456
----------
start by first multiplying 6*3=18. Write down the 8 and carry the 1 mentally.
123
456
---------- CARRY 1
----8
Step 2---- attempt to form an invisible X
It may not sound simple at first but I'll explain.
Start by observing the 6 & 2, then the 5 & 3. Make a line between those numbers and you will get an X.
Now multiple 6*2=12 PLUS(+) 5*3=15
so 12 + 15 = 27
27 + 1 (the carry)= 28
Now write down the 8 and carry the 2 mentally.
123
456
---------- CARRY 2
---88
Step 3--- now examine the numbers 6 & 1, 4 & 3, then in the middle 2 & 5.
Multiply them and add em' all up:
6*1=6 + 4*3=12 + 5*2=10
so 6 + 12 +10 = 28 PLUS carry 2 = 30.
Write down the 0 and carry the 3.
123
456
---------- CARRY 3
--088
Step 4--- Now we will attempt the invisible X for the last time. This time take notice of the numbers 5 & 1, 4 & 2
multiply them and add em' all up:
5*1=5 + 4*2=8
so 5 + 8 = 13 PLUS carry 3 = 16.
Write down the 6 and carry the 1.
123
456
---------- CARRY 1
--6088
Step 5 (final step)--- In the beginning we started by multiplying 6 & 3. Now we will multiply 4 & 1.
so 4*1=4 + carry 1 = 5
Write it down and the behold the FINAL ANSWER!
123
456
----------
56088
Nothing in this world is easy to learn at first shot, so give it some time like I did and become a master at the skill. It just might help you in the long run because I myself can multiply any two 3-digit numbers in my head in less than 5 seconds (using the method I just explained) and I'm getting better. Good luck!
Let’s start with 123 * 456. Echague Isabela
Step 1--- arrange the numbers in order (one on top of the other) your pick.
123
456
----------
start by first multiplying 6*3=18. Write down the 8 and carry the 1 mentally.
123
456
---------- CARRY 1
----8
Step 2---- attempt to form an invisible X
It may not sound simple at first but I'll explain.
Start by observing the 6 & 2, then the 5 & 3. Make a line between those numbers and you will get an X.
Now multiple 6*2=12 PLUS(+) 5*3=15
so 12 + 15 = 27
27 + 1 (the carry)= 28
Now write down the 8 and carry the 2 mentally.
123
456
---------- CARRY 2
---88
Step 3--- now examine the numbers 6 & 1, 4 & 3, then in the middle 2 & 5.
Multiply them and add em' all up:
6*1=6 + 4*3=12 + 5*2=10
so 6 + 12 +10 = 28 PLUS carry 2 = 30.
Write down the 0 and carry the 3.
123
456
---------- CARRY 3
--088
Step 4--- Now we will attempt the invisible X for the last time. This time take notice of the numbers 5 & 1, 4 & 2
multiply them and add em' all up:
5*1=5 + 4*2=8
so 5 + 8 = 13 PLUS carry 3 = 16.
Write down the 6 and carry the 1.
123
456
---------- CARRY 1
--6088
Step 5 (final step)--- In the beginning we started by multiplying 6 & 3. Now we will multiply 4 & 1.
so 4*1=4 + carry 1 = 5
Write it down and the behold the FINAL ANSWER!
123
456
----------
56088
Nothing in this world is easy to learn at first shot, so give it some time like I did and become a master at the skill. It just might help you in the long run because I myself can multiply any two 3-digit numbers in my head in less than 5 seconds (using the method I just explained) and I'm getting better. Good luck!
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