ML Aggarwal CBSE Solutions Class 6 Math Chapter Whole Numbers Exercise 2.3
(1) Using shorter method, find
(i) 3246 + 9999
=> 3246 + 9999 = 3246 + (10,000 – 1) = 13246 – 1 = 13245
(ii) 7501 + 99999
=> 7501 + (100000 – 1) = 107501 – 1 = 107500
(iii) 5377 – 999
=> 5377 – (1000 – 1) = 4377 – 1 = 4376
(iv) 25718 – 9999
=> 25718 – (10000 – 1) = 15718 – 1 = 15717
(v) 123 x 999
= 123 X (1000 – 1) = 123000 – 1 = 122999
(vi) 203 x 9999
= 203 X (10000 – 1)
= 2030000 – 1
= 2029999
(2) Without using a diagram, find
(i) 9th square number
9th Square number is = 9 x 9 = 81
(ii) 7th triangular number
5th triangular number = 15 [1 + 2 + 3 + 4 + 5]
6th triangular number = 15 + 6 [1 + 2 + 3 + 4 + 4 + 6]
= 21
7th triangular number = 21 + 7 = 28
(3) (i) Can a rectangular number be a square number?
Solution: No it cant be because the square number is different from the rectangular number.
(ii) Can a triangular number be a square.
Solution: Yes; 8th triangular number = 36, which is a square number.
(4) Observe the following pattern and fill in the blanks
1 x 9 + 1 = 10
12 x 9 + 2 = 110
123 x 9 + 4 = 1110
1234 x 9 + 4 = 11110
12345 x 9 + 5 = 111110
(5) Observe the following pattern and fill in the blanks:
9 x 9 + 7 = 88
98 x 9 + 6 = 888
987 x 9 + 5 = 8888
9876 x 9 + 4 = 88888
98765 x 9 + 4 = 888888
Very nice solution ML aggarWal