Measurement reporting: The digits in a measured value that are certainly known (plus the properly estimated final digit) are called:

Introduction / Context:
In experimental work and instrument reading, communicating how trustworthy a number is matters as much as the number itself. Significant digits (also called significant figures) encode the certainty of a measurement and the resolution of the measuring instrument, guiding rounding and propagation of uncertainty in calculations.

Given Data / Assumptions:

• A measured value includes digits known with certainty and one last digit that is an estimate.
• We use standard conventions for counting significant digits.
• Terms like accuracy and precision have specific meanings distinct from significant digits.

Concept / Approach:
Significant digits are all nonzero digits, zeros between nonzero digits, and trailing zeros in a decimal number; leading zeros are not significant. They reflect measurement resolution and should be preserved through calculations according to established rules for addition/subtraction and multiplication/division to avoid overstating certainty.

Step-by-Step Solution:

Verification / Alternative check:
Cross-check with instrument specifications: if a digital multimeter is 3.5 digits, its last displayed digit is the least significant and often the estimated/uncertain one, consistent with significant-digit rules.

Why Other Options Are Wrong:

• Accuracy digits/precision digits: Accuracy and precision are performance qualities, not names for the digits themselves.
• Error digits: There is no such standard term; error relates to uncertainty, not a specific set of digits.

Common Pitfalls:
Carrying too many digits through computations (false precision) or rounding too early, which can distort results. Round at the end, respecting the weakest measurement's significant digits.

Final Answer:
significant digits