🏰 Number Kingdom · Significant figures
Recognise zeros that count as significant because they carry measured precision. In this lesson, focus on significant figures describe the important digits in a value.
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Recognise zeros that count as significant because they carry measured precision. In this lesson, focus on significant figures describe the important digits in a value.
Significant figures describe the important digits in a value. Counting starts at the first non-zero digit, not automatically at the decimal point, and zeros inside or after significant digits may matter. For significant zeros, the final written answer should make that exact relationship visible rather than hiding it inside an unexplained result.
Significant zeros: Significant figures describe the important digits in a value. Read the rounded answer back at the original scale and count the significant digits again. Keep the significant zeros representation visible until the final line.
Highlight each digit from the first non-zero digit and classify zeros as leading placeholders or significant information. Use the model to explain one change you notice while working on significant zeros.
Read the rounded answer back at the original scale and count the significant digits again. Write that check beside the final significant zeros answer.
First significant figure = first non-zero digit.
Visual / interactive
Highlight each digit from the first non-zero digit and classify zeros as leading placeholders or significant information. Use the model to explain one change you notice while working on significant zeros.
Worked examples
Understand the idea with small numbers, one representation and one clear step.
Use the standard Year 8 method with mixed examples and normal wording.
Handle multi-step or less familiar questions and explain choices.
Solve a worded question, show reasoning, check accuracy and write a final sentence.
Given information: Significant zeros — Count the significant figures in 0.00408. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: Start at the first non-zero digit and count every digit after it that records precision. 0.00408 has 3 significant figures. Final answer: 3. Check: substitute or compare with the original information to confirm the result fits the question.
Given information: Significant zeros — Does 12.030 contain a zero between significant digits? Answer yes or no. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: A zero sits between non-zero significant digits, so it must be counted. Final answer: yes. Check: substitute or compare with the original information to confirm the result fits the question.
Check: Keep place-value zeros needed to show the size of the number.
Given information: Significant zeros — Write the number of significant figures shown by the measurement 20.05. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: The written measurement records 4 significant figures because counting begins at the first non-zero digit. Final answer: 4. Check: substitute or compare with the original information to confirm the result fits the question.
Try explaining why each step works before checking the answer.
Given information: Significant zeros — Which digit is the first significant figure in 0.00073? Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: Ignore placeholder zeros before the first non-zero digit. The first significant digit is 7. Final answer: 7. Check: substitute or compare with the original information to confirm the result fits the question.
Read the rounded answer back at the original scale and count the significant digits again. Write that check beside the final significant zeros answer.
Create a significant zeros problem with a tempting incorrect answer. Solve it, apply the check, and explain exactly where the incorrect method breaks down.
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Use digit hunt controls to solve three checked significant zeros rounds. Solve at least two of three marked rounds and use feedback to correct any error.
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Significant zeros: Significant figures describe the important digits in a value. Read the rounded answer back at the original scale and count the significant digits again. Keep the significant zeros representation visible until the final line.
Tap to mark reviewedsignificant figure · first non-zero digit · leading zero · placeholder zero · accuracy · significant · zeros
Tap to mark reviewedLocate the first non-zero digit. Count significant digits from left to right. If rounding, circle the final kept digit. Use the next digit to decide whether to round and keep place-value zeros where needed. Record the check explicitly for significant zeros.
Tap to mark reviewedFirst significant figure = first non-zero digit.
Tap to mark reviewedGiven information: Significant zeros — Count the significant figures in 0.00408. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: Start at the first non-zero digit and count every digit after it that records precision. 0.00408 has 3 significant figures. Final answer: 3. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedGiven information: Significant zeros — Does 12.030 contain a zero between significant digits? Answer yes or no. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: A zero sits between non-zero significant digits, so it must be counted. Final answer: yes. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedGiven information: Significant zeros — Write the number of significant figures shown by the measurement 20.05. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: The written measurement records 4 significant figures because counting begins at the first non-zero digit. Final answer: 4. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedGiven information: Significant zeros — Which digit is the first significant figure in 0.00073? Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: Ignore placeholder zeros before the first non-zero digit. The first significant digit is 7. Final answer: 7. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedCounting leading zeros as significant. This is a key trap when answering significant zeros questions.
Tap to mark reviewedFor significant zeros, show the key representation before the final calculation. Use this final check: Read the rounded answer back at the original scale and count the significant digits again.
Tap to mark reviewedScientific measurements, Population estimates
Tap to mark reviewedI can explain significant zeros, use the method, check for mistakes, and answer an exam-style question.
Tap to mark reviewedI’m Stuck
Use this whenever a question feels confusing. Nothing here is locked.
Significant zeros: Significant figures describe the important digits in a value. Read the rounded answer back at the original scale and count the significant digits again. Keep the significant zeros representation visible until the final line.
Think of significant zeros as a careful model: make the important values visible, change one thing at a time, and use the check to prove the answer fits.
Start by naming the given information and the exact result required for significant zeros.
Locate the first non-zero digit.
Given information: Significant zeros — Count the significant figures in 0.00408. Method choice: use the significant zeros method and show each step with the stated values. Calculation or reasoning: Start at the first non-zero digit and count every digit after it that records precision. 0.00408 has 3 significant figures. Final answer: 3. Check: substitute or compare with the original information to confirm the result fits the question.
Method: Locate the first non-zero digit. → Count significant digits from left to right. → If rounding, circle the final kept digit. → Use the next digit to decide whether to round and keep place-value zeros where needed. Record the check explicitly for significant zeros.
Counting leading zeros as significant. This is a key trap when answering significant zeros questions.
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