Special number 1001

In this article I tell you some fast tips to MULTIPLY number by 1001

3 digit number multiply by 1001
If you want to do this you simply write it two times
Example -
456 * 1001 = 456456
348 * 1001 = 348348
237 * 1001 = 237237

2 digit number multiply by 1001
You simply write two times the original number and put 0 between them.
Example -
45 * 1001 = 45045
23 * 1001 = 23023
89 * 1001 = 89089

1 digit number multiply by 1001
It can done very easily.
3 * 1001 = 3003

Facts about 1001
1001 is made by consecutive prime numbers multiplication.
( 7 * 11 * 13)(✷‿✷)(✷‿✷)

3 Likes

That’s brilliant!

Just tried another version of it with 101

so a 3 digit x by 101

123 x 101 = 1 24 23

simply adding 1 to 23 = 24
so the result is 1 24 23

It seems to work with any 3 digit number.

789 x 101
7+89 = 96

so the results
7 96 89

works every time :slight_smile:

Tried with 999 x 101
This time the results is different but the formula seems to be the same.
In fact it’s even easier.

Rather than 9+99
It’s 999+9 = 1008
The result is 1008 99

998 x 101
998+9 = 1007
Result is 1007 98

So all the digits with up to 989 works with adding the digits together.
All the digits from 990, simply adding a 9 works every time.

I’m starting to like maths :slight_smile:

2 Likes

it also seems to work with 4 digits x 101

1234
12+34 = 46

1234 x 101 = 12 46 34

again it’s the same with 9999 x 101
Because it’s 4 digits, instead of adding a single 9, I add 99

99 + 9999 = 10098

9999 x 101 = 10098 99

Works every time. Nice!

1 Like

@Erol
If you multiply any number with 999
Than simply subtract 1and write complement of number
Ex 456 * 999
455 544 (complement of 455 is 544)

Another ex 543 * 999 = 542457
54 * 99 = 5346

23457891466 * 99999999999
= 2345789146576542108534 is the correct answer.
This method is made by Indian mathematician Srininivasa Ramanujan ( my favorite mathematician)

2 Likes

I don’t get this.
How do you get 544 ?

.
This might help:
.

1 Like

It’s just simple
4 5 5 which number I add to do this that it becomes nine
Parammitra ( Best friend )
List of parammitra
1 - 8
2 - 7
3 - 6
4 - 5
0 - 9
And reverse is same
So I do this
455+544 = 999

2 Likes

Got it!
That’s very clever.
Seems easy when you know how :slight_smile: