Lesson: Squaring Numbers Ending in 5

Comment on Squaring Numbers Ending in 5

Does this work if the base is negative?
gmat-admin's picture

Yes. Keep in mind that x² = (-x)².

For example, 3² = 9, and (-3)² = 9.

Likewise, 35² = (-35)² = 1225, and 65² = (-65)² = 4225

Sir, How can we Find Last 2 Digit and Last unit of a number whenever it is multiplied , Divided, Subtracted or Added in to any other number?
gmat-admin's picture

The last (units) digit is pretty straightforward, but in most cases, the last 2 digits is outside the scope of the GMAT.

Does this technique is also useful for squares higher than 2 (i.e. 25^3)
gmat-admin's picture

Good question.

The answer is no; the technique can't be extended to powers other than 2.

I think this technique can only be used for numbers ending in 5? I tried with 6, for example- 76 and it didn't work.
gmat-admin's picture

That's correct; the technique works on for numbers ending in 5 (thus the title :-)

Majestic!
gmat-admin's picture

Indeed :-)

Amazing!

Add a comment

Tweet about the course!

If you're enjoying my video course, help spread the word on Twitter.

Office Hours

Have questions about your preparation or an upcoming test? Need help modifying the Study Plan to meet your unique needs? No problem. Just book a Skype meeting with Brent to discuss these and any other questions you may have. 

Have a question about this video?

Post your question in the Comment section below, and I’ll answer it as fast as humanly possible.

Free “Question of the Day” emails!