Whether you’re trying to plan your next birthday party or looking ahead to your wedding anniversary, you’ll quickly find yourself wondering what day of the week the milestone will fall on.
And while there’s always the calendar on your phone to help you plan, wouldn’t it be great if you could quickly work out the relevant date in your head?
Well, thanks to a mathematical trick, previously explained on Forbes‘ website, now you can.
The trick, dubbed Zeller’s formula, gives you the day of the week for any date by 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, with zero meaning Sunday, one referring to Monday and so on, until you get Saturday as six, and k is the date of the month, D is 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 instance, if you want to work out which day December 7, 1941 fell on, you would use the terms as so: k = 7, D = 41, C = 19, m = 10.
It works out to show the formula as d=7+[(13×10-1)/5]+41+[41/4]+[19/4]-2×19 mod 7. If you work out the sums in the brackets first, 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 ahead to your wedding anniversary, you’ll quickly find yourself wondering what day of the week the milestone will fall on (stock photo)
Ultimately, the sum gets to 0 mod 7, meaning 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 to near enough to 15+7+93+23+4-38 mod 7. Once correctly worked out, it would give you the number six, meaning that date fell on a Saturday.
Meanwhile, if you think you’re a maths whiz with razor-sharp observation skills, then this puzzle may have been made just for you.
In this tricky brainteaser, puzzlers are challenged to find a hidden number in seconds – so, can you locate it before the timer ends?
Immerse Education unveiled the new brainteaser that’s challenging even the brightest minds.
The task is to locate a hidden number amidst a sea of identical sequences in under 30 seconds. If you can, you might just have a high IQ.
This deceptively simple puzzle features rows and rows of the number 383, with one sequence standing out from the rest.
And while there’s always the calendar on your phone to help you plan, wouldn’t it be great if you could quickly work out the relevant date in your head? Well, thanks to a mathematical trick, previously explained on Forbes ‘ website, now you can (stock photo)
In this tricky brainteaser, puzzlers are challenged to find a hidden number in 30 seconds – so, can you locate it before the timer ends?
Your mission, should you choose to accept it, is to find the odd one out in less than a minute.
While it sounds easy, the uniformity of the numbers can trick your eyes, making it much harder than it appears.
Ready to test your skills? Set your timer and put on your glasses. If you need a little help, try zooming in on the image.
Finding the hidden number requires keen eyesight, an attentive mind and quick thinking.
If you spotted it within the time limit, congratulations! You’ve got enviable observational skills.
If you’re still struggling to locate it, don’t worry, as we’ve provided the answer below.
Avert your eyes to the left side of the image and scan down to the eleventh row. Count three numbers from the left and you’ll find the sequence ‘363’ amidst the sea of 383s
Avert your eyes to the left side of the image and scan down to the eleventh row.
Count three numbers from the left and you’ll find the sequence ‘363’ amidst the sea of 383s.
