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Class 9 The World of Numbers worksheet
CBSE Mathematics. Irrational numbers, surds, rationalising, real exponents. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
Which of these is irrational?
- √20
- √49
- 2/4
- 0.87
Answer
(a) √20
20 is not a perfect square
- 2.
The decimal expansion of 4/15 is:
- terminating
- cannot be found
- non-terminating non-repeating
- non-terminating repeating
Answer
(d) non-terminating repeating
the denominator 15 has a prime factor other than 2 and 5
- 3.
(√11 + √23)(√11 − √23) equals:
- 12
- √253
- 34
- −12
Answer
(d) −12
(√11)² − (√23)² = 11 − 23
Section B · short answer
- 4.
Rationalise the denominator: 1/(6 + √10)
Answer
(6 − √10)/26
multiply by (6 − √10); denominator 6² − 10 = 26
- 5.
Simplify: 4√5 + 4√20
Answer
12√5
√20 = 2√5, so 4√5 + 8√5 = 12√5
Section C · long answer
- 6.
A square plot has an area of 200 m². Find the length of its side in simplest surd form.
Answer
10√2 m
side = √200 = √(100 × 2) = 10√2
Fresh sheets for your child
In the app, every The World of Numbers sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
Coming soon for Android and iPhone.