Can't do 23*23 in my head is this natural?

Question

I know how to do 23*23 on paper, but not in my head. I only know that it ends with a 9. in my head is this natural???

I know how to remember
1²-17²
17²=289
18²=324
19²=361
20²=400
21²=441
22²=484
23²=beats me

IM 15, IM 15
READ PLEASE

Answer 1

And i thought remembering 12 x 12 was difficult... lol.... don't worry about it

Answer 2

Don't "remember" it, find an alternate method... If you give it some thought, you can arrive to a quick multiplication method. For instance:
23*23 =

2*2 2*3+3*2 3*3
4 12 9
4+1 <-- 2 9
5 2 9

Answer 3

Here is a cool trick in which you can easily do it in your head.

23*23. First, multiply the last digits of each number together. In this case it is 9, so the last number of the total is 9. Next you do sort of a criss cross method, multiply them and add them. 2*3+2*3 which would be 12. Now you only use the 2 for now, and just remember the 1. (The last 2 digits are 29). Now multiply the first 2 digits, and then add that 1. 529 should be the answer.

This works for any 2 digit number multiplied by a 2 digit number. There is a similar trick for 3 numbers, but it is more difficult.

Hope this trick helps you.

Answer 4

17^2 = 17 (17)
7(7) = 49 . . . . place the 9 in the unit column. . . carry 4
1(7)+ 7(1) + 4 = 18 . . . . . cross-multiply the digits + carry
. . . . . . . . . . . . . place the 8 in the tens column, carry 1
1(1) + 1 = 2 . . . . . . . . place the 2 in the hundred
answer 289

23^2 = 23 (23)
3(3) = 9 . . . . place the 9 in the unit column. . . no carry
2(3)+ 3(2) = 12 . . . . . cross-multiply the digits
. . . . . . . . . . . . . place the 2 in the tens column, carry 1
2(2) + 1 = 5 . . . . . . . . place the 5 in the hundred
answer 529

Answer 5

If you can't simply memorize it, you might be able to compute it in your head by breaking it into pieces:

23*23 = 23*(20 + 3) = 23*20 + 23*3

23*20 = 23*2*10 = 46*10 = 460, which isn't too hard.
23*3 is 69, which isn't hard, either.
Adding 460 and 69, you get 529, which is the correct answer.

Answer 6

Well, if you think for a little bit, in your head, you could think this:
20*20=400
20*3=60
20*3=60
3*3=9
400+60+60+9=529
If you break it into simple parts, it is not very hard, unless your memory isn't that good.
But it is pretty normal if you can't. Sometimes I have to do problems in my head and I keep forgeting the numbers.
Paper or calculator are fine!

Answer 7

324 + 37 = 361 which equals 19x19

361 + 39 = 400 which equals 20x20

400 + 41 = 441 which equals 21x21

441 + 43 = 484 which equals 22x22

Therefore,

484 + 45 = 529 which equals 23x23.


See the pattern? 37,39,41,43,45. Increments of two.

Answer 8

Hey there!

It is natural to everyone. One person can be a scientist but does not know how to multiply large numbers. Another can be a hobo but knows how to multiply large numbers. See the difference? One person may have an awesome career but does not know how to do simple math whereas another person knows how to do it. Don't worry if you don't know it.

By the way the answer is 529.

Hope it helps!

Answer 9

After some effort I got 460 + 69 = 529
But I cheated.

Answer 10

Doing multiplication in your head is a mental trick and nothing to do with IQ. There are idiot savants who can do incredible feats of mental arithmetic but cannot tie their own shoelaces.

It is far more important that you know how to do it on paper or with a calculator than that you do it in your head.

Answer 11

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