9 Is Considered a "Magic" Number
Have you ever heard that the number 9 is considered to be a "magic" number? No? Well it is, and here is why: if you multiply a number by 9 and add all the digits of the new number together, the sum will always add up to 9 or its multiples . So, for example:
8 x 9 = 72
7 + 2 = 9
Or:
4 x 9 = 36
3 + 6 = 9
See? It truly is magical. Try it out. Every single combination will always lead you back to 9 or its multiple !@maths_sorcerer
Have you ever heard that the number 9 is considered to be a "magic" number? No? Well it is, and here is why: if you multiply a number by 9 and add all the digits of the new number together, the sum will always add up to 9 or its multiples . So, for example:
8 x 9 = 72
7 + 2 = 9
Or:
4 x 9 = 36
3 + 6 = 9
See? It truly is magical. Try it out. Every single combination will always lead you back to 9 or its multiple !@maths_sorcerer
In A Group Of 23 People, Two Will Probably Share a Birthday
In a sample of 23 people, there is a 50 percent chance that two will share the same birthday. This phenomenon is (fittingly) called the birthday problem. There is a whole calculation for why this is a thing, too. It all has to do with probability. For how, exactly, it works, direct yourself to this explainer, by mathematician Brett Berry, as she can do a far better job at explaining it than we ever could.
In a sample of 23 people, there is a 50 percent chance that two will share the same birthday. This phenomenon is (fittingly) called the birthday problem. There is a whole calculation for why this is a thing, too. It all has to do with probability. For how, exactly, it works, direct yourself to this explainer, by mathematician Brett Berry, as she can do a far better job at explaining it than we ever could.
The answer is always 6174
Starting with any four digit number (that has at least two different digits) just follow the following steps:
1. Arrange the digits of the four digit number in descending/ascending order to make the largest and smallest numbers possible.
2. Subtract the smaller number from the larger one.
3. Take the answer and repeat the process.
Eventually you'll end up at 6174 or 'Kaprekar's Constant'. Just as remarkable, it never takes more than seven stages to get there.
Picking a number at random, let's try 4551, for instance.
Stage 1: 5541-1455 = 4086
Stage 2: 8640 - 0468 = 8172
Stage 3: 8721 - 1278 = 7443
Stage 4: 7443 - 3447 = 3996
Stage 5: 9963 - 3699 = 6264
Stage 6: 6642 - 2466 = 4176
Stage 7: 7641 - 1467 = 6174
@maths_sorcerer
Starting with any four digit number (that has at least two different digits) just follow the following steps:
1. Arrange the digits of the four digit number in descending/ascending order to make the largest and smallest numbers possible.
2. Subtract the smaller number from the larger one.
3. Take the answer and repeat the process.
Eventually you'll end up at 6174 or 'Kaprekar's Constant'. Just as remarkable, it never takes more than seven stages to get there.
Picking a number at random, let's try 4551, for instance.
Stage 1: 5541-1455 = 4086
Stage 2: 8640 - 0468 = 8172
Stage 3: 8721 - 1278 = 7443
Stage 4: 7443 - 3447 = 3996
Stage 5: 9963 - 3699 = 6264
Stage 6: 6642 - 2466 = 4176
Stage 7: 7641 - 1467 = 6174
@maths_sorcerer
Armstrong number
An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number since 3³ + 7³ + 1³ = 371.
@maths_sorcerer
An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number since 3³ + 7³ + 1³ = 371.
@maths_sorcerer
Teenagers texting in Thailand will send the digits 555 to indicate that something is funny. In the Thai language, 5 is pronounced as ha which when translated becomes ha-ha-ha.
@maths_sorcerer
@maths_sorcerer
A useful trick for percentages.
Did you know that x% of y = y% of x?
This can make working out percentages a much easier task. For example, try to calculate 8% of 50 in your head. Not so easy right. Now flip it and instead work out 50% of 8, I think it’s clear which is easier.
Similarly, 32% of 75 may seem difficult to calculate, but 75% of 32 seems a much easier challenge
@maths_sorcerer
Did you know that x% of y = y% of x?
This can make working out percentages a much easier task. For example, try to calculate 8% of 50 in your head. Not so easy right. Now flip it and instead work out 50% of 8, I think it’s clear which is easier.
Similarly, 32% of 75 may seem difficult to calculate, but 75% of 32 seems a much easier challenge
@maths_sorcerer