Important Pythagorean Triplets

"As you know these are very crucial to memorize. Even if you know how to find these triplets you should directly predict the third when 2 of them is given.
It is much essential in your exam point of you.
In almost all cases, I will recommend that student learn to remember mathematical facts without memorizing them. This is one of the few cases in which I will unapologetically recommend memorizing. There are certain sets of positive integers that satisfy the Pythagorean Theorem: these sets of three integers are called Pythagorean triplets. Some of them are very obscure, but some of them are extremely common. The most common by far is the triplet (3, 4, 5). In all of these, I am listing a set (a, b, c) that satisfies a^2 + b^2 = c^2, so the largest number would be the hypotenuse of the triangle. Two other common sets of Pythagorean triplets are (5, 12, 13) and (8, 15, 17). Right there, BAM! Memorize those three sets, and you will spare yourself many stressful moments of lengthy calculations on the GMAT Quantitative section, when you have no calculator.

First of all, if you encounter a right triangle with legs 8 & 15, you won’t have to square and add things up: rather, you will just know that the hypotenuse is 17. The benefits, though, of that wee bit of memorizing expend wildly when you realize: you can multiply any of those three sets by any integer and get a new set of Pythagorean Triplets. The first set, (3, 4, 5), is the most common to see in multiplies —- (6, 8, 10), (9, 12, 15), (12, 16, 20), etc. —- but once in a while you may see one of the other two multiplied by something small, like 2 or 3

Kindly memorize the most frequently used ones:"