Class 7 Standard Form — practice questions with answers
Number System · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
1. A number written as k x 10^n is said to be in standard form when k satisfies which condition?
A1 <= k < 10
B0 < k < 1
C1 < k <= 10
Dk is any whole number
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Answer: A) 1 <= k < 10
In standard form (scientific notation) the first factor k must be at least 1 and less than 10, i.e. 1 <= k < 10.
2. Write 9030 in standard form.
A9.03 x 10³
B9.3 x 10³
C90.3 x 10²
D9.03 x 10²
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Answer: A) 9.03 x 10³
9030 = 9.030 x 1000 = 9.03 x 10³. The middle zero is kept.
3. A school in Pune ordered 24,000 notebooks for its students. The librarian wants to record this quantity in standard form on the stock register. Which entry should she write?
A2.4 x 10⁴
B24 x 10³
C2.4 x 10³
D2.4 x 10⁵
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Answer: A) 2.4 x 10⁴
24000 = 2.4 x 10000 = 2.4 x 10⁴.
4. The number line below marks powers of ten: 10¹, 10², 10³, 10⁴. The value 3000 lies between two of these marks. In standard form, 3000 is written as which of the following?
A3 x 10³
B3 x 10⁴
C30 x 10²
D3 x 10²
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Answer: A) 3 x 10³
3000 = 3 x 1000 = 3 x 10³, which sits at the 10³ region of the line.
5. A number written in standard form as k x 10⁷ lies between one crore and ten crore. If the number is exactly 6,30,00,000 (six crore thirty lakh), find the value of k. Give k as a decimal.
A5.3
B7.3
C12.6
D6.3
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Answer: D) 6.3
Six crore thirty lakh = 63000000 = 6.3 x 10⁷, so k = 6.3.