Whether you’re trying to plan your next birthday party or looking ahead to your wedding anniversary, you’ll quickly wonder what day of the week the milestone will fall on.
And while you always have the calendar on your phone to help you plan, wouldn’t it be great if you could quickly calculate the relevant date in your head?
Well, thanks to a mathematical trick, explained previously in Forbes‘ website, now you can do it.
The trick, called the Zeller formula, gives you the day of the week for any date using this method: d=k+((13m-1)/5)+D+(D/4)+(C/4)-2C mod 7.
The terms are defined as d being the day of the week, where zero means Sunday, one refers to Monday and so on, until Saturday is obtained as six, and k is the date of the month, D are the last two numbers of the year and C is the century.
However, January and February are the 11th and 12th months, since the trick only works if you count March as number one.
For example, if you wanted to calculate what day December 7, 1941 fell on, you would use the terms like this: k = 7, D = 41, C = 19, m = 10.
It works to display the formula as d=7+((13×10-1)/5)+41+(41/4)+(19/4)-2×19 mod 7. If you first calculate the sums in parentheses, this will leave you with 7+25+41+10+4-38 mod 7.
Whether you’re trying to plan your next birthday party or looking forward to your wedding anniversary, you’ll quickly wonder what day of the week the milestone will fall on (file photo)
In the end, the sum reaches 0 mod 7, which means that the day was Sunday.
Another example would be May 15, 1993. The sum would be d=15+((13×3-1)/5)+93+(93/4)+(19/4)-2×19 mod 7.
This would get you close enough to 15+7+93+23+4-38 mod 7. Once calculated correctly, it would give you the number six, meaning that date fell on a Saturday.
Meanwhile, if you think you’re a math whiz with sharp observation skills, then this puzzle may have been made just for you.
In this tricky puzzle, participants are challenged to find a hidden number in seconds. So, can you locate him before the timer runs out?
Immerse Education introduced the new puzzle that challenges even the brightest minds.
The task is to locate a hidden number in the middle of a sea of identical sequences in less than 30 seconds. If you can, you may have a high IQ.
This deceptively simple puzzle features rows and rows of the number 383, with one sequence that stands out from the rest.

And while you always have the calendar on your phone to help you plan, wouldn’t it be great if you could quickly calculate the relevant date in your head? Well, thanks to a mathematical trick, previously explained on the Forbes website, you now can (file photo)

In this tricky puzzle, participants are challenged to find a hidden number within 30 seconds. So, can you locate him before the timer runs out?
Your mission, if you decide to accept it, is to find the stranger in less than a minute.
Although it may seem easy, the uniformity of the numbers can deceive the eye, making it much more difficult than it seems.
Ready to test your skills? Set your stopwatch and put on your glasses. If you need a little help, try enlarging the image.
Finding the hidden number requires sharp eyesight, an attentive mind and quick thinking.
If you saw it within the time limit, congratulations! You have enviable observation skills.
If you are still having difficulty locating it, don’t worry as we have provided the answer below.

Look to the left side of the image and scan to the eleventh row. Count three numbers from the left and you will find the sequence ‘363’ in the middle of the sea of 383.
Look to the left side of the image and scan to the eleventh row.
Count three numbers from the left and you will find the sequence ‘363’ in the middle of the sea of 383.