Neat Math Trick

[boyntonstu]

A neat math trick.



All of these numbers are very easy to square (multiply by itself).



15,25,35,45,55,65,75,85,95.



First thing to remember is that all the answers end in 25.



Let’s do 35 x 35.



Don’t look at the 5, just the digit before 5, in this case 3.



The next digit up from 3 is 4. Multiply 3 x 4.



3 x 4 is 12. Tack on 25.



Therefore 35 x 35 is 1225. (all answers end in 25)



Next example:



45 x 45 is 2025. 4 x 5 is 20 and just tack on 25 to the 20 to get 2025.

[jrrdw]

How does this tie into spudding? Or the building of spudguns?

[boyntonstu]

Does it fit here?

Non-Spudgun Related Discussion

[Ragnarok]

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.

Doesn't seem like a project, theory or serious question to me, Stu.

[boyntonstu]

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.

Doesn't seem like a project, theory or serious question to me, Stu.

Topics like these?

How fast can you type/click?

If you have been busted by the cops or arrested you may post your story but keep it legit and have a reason behind it.

Need help fixing brakes on trials bike.

Applying to College

[velocity3x]

45 x 45 is 2025. 4 x 5 is 20 and just tack on 25 to the 20 to get 2025.

I don't know....I'm not from around here.

[Ragnarok]

How fast can you type/click?

Later locked for being off-topic.

If you have been busted by the cops or arrested you may post your story but keep it legit and have a reason behind it.

Emphasis on "have a reason behind it" - this is largely intended to help others avoid the same misfortune.

Need help fixing brakes on trials bike.

Valid project involving a serious question that people here may have advice for.

Applying to College

Serious question that people here may have experience on.

[boyntonstu]

How fast can you type/click?

Later locked for being off-topic.

If you have been busted by the cops or arrested you may post your story but keep it legit and have a reason behind it.

Emphasis on "have a reason behind it" - this is largely intended to help others avoid the same misfortune.

Need help fixing brakes on trials bike.

Valid project involving a serious question that people here may have advice for.

Applying to College

Serious question that people here may have experience on.

Great answer. We need you. Keep up the great work!

[jrrdw]

Well there has been nothing else about the math. If another moderator or PCGUY wants it back open...so be it.