Square root
Let us now see how to find the square root of perfect square numbers. Finding the square root is real easy once we know certain basic rules. Memorising the table of squares is the key to easy calculation.
Table of squares.
From the above table we can conclude the following:
Squares of 1 and 9 end in 1.
Squares of 2 and 8 end in 4.
Squares of 3 and 7 end in 9.
Squares of 4 and 6 and in 6.
Square of 5 always end in 25.
The numbers ending in 2,3,7,8 are not perfect squares.
Using the above points look at the following squares:
512= 2601 692 = 4761
422 = 1764 782 = 6084
632 = 3969 572 = 3249
442 = 1936 362 = 1296
These examples help us get familiar with the numbers and the units digit of their squares. Now the task for this week is to find squares of many numbers and compare the units digit of their squares.
Logical thinking
Now for some logical thinking. Do you remember the question about sending a valuable gift to your friend? Here is another question, which is a fun way to improve logical and analytical ablilities.
Four friends – Lekha, Fathima, Pinky and Charu – went to a pet shop. They purchased a cat, a puppy, love birds and fish. Now using the clues below you have to find which pet was bought by each one.
No one bought a pet whose name starts with the same letter as their name.
Charu does not have an aquarium in her house.
Lekha is allergic to the hair of pet animals.
Fathima loves birds.
Got any idea how to solve it?
First check the first letter of the friends' names against the pets.
From the second clue we can decide that Charu did not buy fish.
The next clue tells us that Lekha did not buy a puppy or a cat.
The last clue tells us that Fathima bought the love birds.
This means none of the others have brought love birds.
And we see that Lekha’s allergy leaves her with the fish.
Pinky is left with the cat since 'puppy starts with p.
The remaining person is Charu and her pet is the puppy.
Tip of the week: To find the square root we need to think logically.