Exercise 5.1
- What will be the unit digit of the squares of the following numbers?
- The following numbers are obviously not perfect squares. Give reason.
Condition: Natural numbers ending in the digits , , , and are not perfect squares. (Enter numbers in increasing order)
(i) 1057 a perfect square as it with the digit .
(ii) 23453 a perfect square as it with the digit .
(iii) 7928 a perfect square as it with the digit .
(iv) 222222 a perfect square as it with the digit .
(v) 64000 a perfect square as it with the digit and the number of zeroes at the end are .
(vi) 89722 a perfect square as it with the digit .
(vii) 222000 a perfect square as it with the digit and the number of zeroes at the end are .
(viii) 505050 a perfect square as it with the digit and the number of zeroes at the end are .
- The squares of which of the following would be odd numbers?
431
2826
7779
82004
Odd
Not Odd
- Observe the following pattern and find the missing digits.
gives us 121.11 2 gives us 10201.101 2 - Further on,
gives us 1002001. You might have notice a pattern.1001 2 - Now, we get:
=100001 2 . - And
=10000001 2 . - We have completed the pattern.
- Observe the following pattern and supply the missing numbers.
gives us 121.11 2 gives us 10201.101 2 - Further on,
gives us 102030201. You might have notice a pattern.10101 2 - Now, we get:
=1010101 2 . - And
= 1020304050403020. - We have completed the pattern.
- Using the given pattern, find the missing numbers.
- Notice the above pattern.
- Further on, we have.
- The even further sequence is as shown. You might have notice a pattern.
- Now, we get:
4 2 + 5 2 + = 21 2 +5 2 + =30 2 31 2 6 2 + +7 2 = - We have completed the pattern.
- Without adding, find the sum:
(i) 1 + 3 + 5 + 7 + 9
Since, we have the sum of the first five odd numbers, the result is i.e. .
(ii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19
Since, we have the sum of the first odd numbers, the result is i.e. .
(iii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23
Since, we have the sum of the first odd numbers, the result is i.e. .
- (i) Express 49 as the sum of 7 odd numbers.
(ii) Express 121 as the sum of 11 odd numbers.
Express 49 as the sum of 7 odd numbers.
Sum of first n odd natural numbers is . We also have 49 =
Upon, solving we get , 49 = + + + + + + i.e. the sum of the first odd numbers.
Express 121 as the sum of 11 odd numbers.
We know that 121 =
Upon, solving we get , 49 = + + + + + + + + + + i.e. the sum of the first odd numbers.
- How many numbers lie between squares of the following numbers?
(i) 12 and 13
We know 12 2 = and 13 2 = . So, a total of numbers lie in between.
(ii) 25 and 26
We know 25 2 = and 26 2 = . So, a total of numbers lie in between.
(iii) 99 and 100
We know 99 2 = and 100 2 = . So, a total of numbers lie in between.