How many significant figures are in 0.00450?

There are three: 4, 5 and the final 0. The leading zeros locate the decimal point. A trailing zero after the decimal point states measured precision and is significant.

Why is 5.0 accepted but 5 marked incorrect?

For 2.50 multiplied by 2.0, the result needs two significant figures, so it is written 5.0. The value 5 has only one written significant figure. Equivalent scientific forms such as 5.0e0 or 0.50e1 are accepted when both value and the last stated decimal place match.

How do the arithmetic and rounding rules work?

Addition and subtraction round to the least precise decimal place among the inputs. Multiplication and division keep the fewest significant figures. Decimal integer coefficients and exact rational division avoid binary floating-point tie errors. This quiz uses round-half-away-from-zero: 1.005 to three figures becomes 1.01, and -1.005 becomes -1.01.

How should I write numbers with trailing integer zeros?

Use explicit scientific notation, such as 1.50e3 for three significant figures, or a terminal decimal point such as 1500. for four. An integer like 1500 is rejected as ambiguous. Type e notation without separators or extra text. Generated questions avoid zero-only counting and division by zero.

Can I print a quiz and review mistakes?

Start a quiz, then choose Print quiz and key. Questions and the full answer key are separate print sections, with the key starting on a new page. Opening a key during a challenge makes that attempt assisted practice. After completion, Practice missed rules repeats incorrect and unanswered questions in their original order. Early end reports attempted, incorrect and unanswered counts separately.

What makes a score eligible for a challenge link?

Complete a fresh untimed 20-question challenge with five questions from each rule group. First answers count, typed entry and the four seeded choices use the same marking rule, and higher correct counts are better. Reveal, print-key access during play, early finish and same-seed or reviewed replay disable scored sharing. A recipient starts explicitly, sees the score difference after finishing, and can reshare their own eligible result. Scores are self-reported; no answers or scores are sent to analytics.

What is saved in my browser?

Only valid practice settings are remembered after you change them. Hidden questions, typed responses and finished scores are not restored. Quizzes contain 1 to 100 questions; challenge quizzes always contain 20.

Significant Figures Practice

Choose counting, rounding, addition/subtraction or multiplication/division practice and generate a seeded quiz with decimal or scientific notation. Type answers or choose from four options, then review each result with its precision rule. A fixed 20-question challenge lets another person attempt the same questions and compare self-reported scores.

Exact decimal arithmetic. Halfway values round away from zero, including negative values. Answers must show their precision.

Question count (1 to 100)NotationAnswer formatSeed (optional)

Practice rules

Precision, not just value

5.0

For 2.50 × 2.0, the result is 5.0: two significant figures. Writing 5 states only one. Equivalent forms such as 5.0e0 are accepted with the same precision.

Use explicit scientific notation for trailing integer zeros: 1.50e3 states three figures. A written terminal point, 1500., states four.

Nothing is scored on this initial example. Choose a mode and start a quiz.

Worked examples

Counting0.00450
3 significant figures
Addition12.11 + 0.3
12.4, one decimal place
Multiplication2.50 × 2.0
5.0, two significant figures

Accuracy. Exact decimal arithmetic applies round-half-away-from-zero and checks both value and stated precision. Ambiguous trailing integer zeros need explicit notation. This is numerical practice, not laboratory or safety advice.

Common questions

How many significant figures are in 0.00450?: There are three: 4, 5 and the final 0. The leading zeros locate the decimal point. A trailing zero after the decimal point states measured precision and is significant.
Why is 5.0 accepted but 5 marked incorrect?: For 2.50 multiplied by 2.0, the result needs two significant figures, so it is written 5.0. The value 5 has only one written significant figure. Equivalent scientific forms such as 5.0e0 or 0.50e1 are accepted when both value and the last stated decimal place match.
How do the arithmetic and rounding rules work?: Addition and subtraction round to the least precise decimal place among the inputs. Multiplication and division keep the fewest significant figures. Decimal integer coefficients and exact rational division avoid binary floating-point tie errors. This quiz uses round-half-away-from-zero: 1.005 to three figures becomes 1.01, and -1.005 becomes -1.01.
How should I write numbers with trailing integer zeros?: Use explicit scientific notation, such as 1.50e3 for three significant figures, or a terminal decimal point such as 1500. for four. An integer like 1500 is rejected as ambiguous. Type e notation without separators or extra text. Generated questions avoid zero-only counting and division by zero.
Can I print a quiz and review mistakes?: Start a quiz, then choose Print quiz and key. Questions and the full answer key are separate print sections, with the key starting on a new page. Opening a key during a challenge makes that attempt assisted practice. After completion, Practice missed rules repeats incorrect and unanswered questions in their original order. Early end reports attempted, incorrect and unanswered counts separately.
What makes a score eligible for a challenge link?: Complete a fresh untimed 20-question challenge with five questions from each rule group. First answers count, typed entry and the four seeded choices use the same marking rule, and higher correct counts are better. Reveal, print-key access during play, early finish and same-seed or reviewed replay disable scored sharing. A recipient starts explicitly, sees the score difference after finishing, and can reshare their own eligible result. Scores are self-reported; no answers or scores are sent to analytics.
What is saved in my browser?: Only valid practice settings are remembered after you change them. Hidden questions, typed responses and finished scores are not restored. Quizzes contain 1 to 100 questions; challenge quizzes always contain 20.

Exact decimal arithmetic applies round-half-away-from-zero and checks both value and stated precision. Ambiguous trailing integer zeros need explicit notation. This is numerical practice, not laboratory or safety advice.