give me some math tricks?

Question

Such as:any multibles of nine when added together equals 9.(this only works on single diget multipliers)
Example 9x1=9 (9+0=9)
9x2=18(1+8=9)
9x3=27(2+7=9)

Answer 1

0
1
2
3
4
5
6
7
8
9

then reverse the order and put beside the first column.....

09
18
27
36
45
54
63
72
81
90

= table of 9's

Answer 2

I you want to know whether a big number is divisible by 3, just add the digits of the number. If the result is divisible by 3, then the original number is, too. It won't give you the answer, but it will tell you whether it comes out even.

Ex. 312756978 3+1+2+7+5+6+9+7+8 = 48. Still don't know for sure? 4+8 = 12. Still? 1+2=3 that is divisible by 3. For sure.

The same works with 9.

Ex. 1307367 1+3+0+7+3+6+7 = 27. Not sure? 2+7=9

See?

Answer 3

Super Speedy Addition
To start: Tell a friend that you have become really fast at addition. To prove it, you will add five 3-digit in your head in a couple seconds.
Materials: calculaator

Showing off your Skills:

1. Tell your friend to write a 3-digit number on a scrap of paper.
Every number must not be the same.

2. Tell your friend to repeat step 1. The same rules apply.

3. Last number. This is the number you notice of thiers.

4. Now comes your part. Write a number so when you add up thier first number and yours it equals 999.

5. Write one more so that the second number of thiers and your second number equals 999 again.

6 Wait a bit. Then give the sum of the 3 numbers they wrote down and the two you did.

7. Why does this trick work?

Look at our trials:

Example
Number one:
693
349
809
306
+650
2807 Example Number two:
867
204
140
132
+795
2138 Example
Number three:
912
786
987
087
+213
2985

Answer 4

when multiplying two digit numbers with single digit numbers, like 35*7

first take 30*7 (since the thirty is in the tens place just put a zero after the 21 so its 210) then multiply 5*7=35 (its in the ones place so theres no zero just multiply as is)

then add them together

210+35=245
35*7=245

if you do 3 digit numbers like 213*6 then do the same thing the 2 is in the hundreds place so add two zeros after the outcome and so on (do that for every number you multiply in your head)

6*200=1200
6*10=60
6*3=18

1200+60+18=1278

213*6=1278 get the picture?

and every multiple of 9 will equal nine just like every multiple of 3 will equal a multiple of three when the numbers are added together 18=9 9 is a multiple of three 2*3 is 6 6 is a multiple of three.

have a wonderful day! check ya later ♥

Answer 5

i only know this one, not sure if it will help.

"finger method x9"
let's say...
5 x 9
hold out your hands, palms facing you. next you count your fingers, left to right. stop once you hit five (or ex: 7 x 9, stop at finger # 7). put the finger you stopped at (5) down. as you will see, on your left hand you have 4 fingers still up. on the other you have 5 fingers up.
put 4 and 5 together and you get 45!
5 x 9 = 45

Answer 6

challenge anyone to name a large number and you can add up the total (1-that number) faster than they can on a calculator:
{(number/2)+.5} x number
example 100:
100/2=50
50+.5 =50.5
50.5 x 100 = 5050!
they will be on their 10th number when you are done!

Answer 7

Wait...i thought it would work on some higher ones like 12x9=108 and 13x9= 117...and 249x9=2241 doesnt it?

Answer 8

use two square to seperate 9 cows.

Answer 9

this has more to do woth patterns than with nimbers but
what do these have in common?
w, u, o, s, k, z, x, c, v

Answer 10

Puff you are good