错误做法:

Using a value <1 or ≥10 in final answer, e.g. writing 12 × 10⁵ instead of 1.2 × 10⁶

原因:

Forgetting the strict range rule for a, which costs 1 formatting mark even if the calculation is correct

正确做法:

After any calculation, adjust the exponent: add 1 if a ≥10, subtract 1 if a <1, until a is in the 1 ≤ a <10 range

错误做法:

Adding/subtracting standard form numbers without aligning powers first, e.g. 3.2×10⁴ + 1.5×10³ = 4.7×10⁷

原因:

Mixing up addition and multiplication exponent rules, leading to completely incorrect results

正确做法:

Rewrite both numbers to have the same power of 10 first, then add/subtract only the a values

错误做法:

Using positive exponents for numbers less than 1, e.g. writing 0.0023 as 2.3×10³

原因:

Confusing direction of decimal movement for small vs large numbers

正确做法:

If you move the decimal point right to get a between 1 and 10, the exponent is negative

错误做法:

Copying calculator E notation directly into exam answers, e.g. writing 5.2E5 instead of 5.2×10⁵

原因:

Exam boards do not accept E notation as valid standard form, so you will lose marks even if the value is correct

正确做法:

Always translate E notation to proper a×10ⁿ form, e.g. 5.2E-3 = 5.2×10⁻³

错误做法:

Forgetting to convert units in word problems, e.g. using time in minutes instead of seconds for speed calculations

原因:

Multi-step problems often require unit conversion first, leading to wrong exponents if skipped

正确做法:

Read the question carefully, convert all units to match the required output before performing standard form calculations